WHEN Alex McLeish was deciding whether to sign Dado Prso for Rangers three years ago he claimed that one of the criteria he used for any potential signing was what he saw when he "looked in the whites of their eyes".

It was an instinct that served Rangers soundly with Prso, and current manager Walter Smith will doubtless make a similar judgement call as he tries to land a replacement when the Croatian surrenders to his battered limbs and leaves next month.

The widespread belief that Rangers must deliver a "new Prso" is understandable but Smith's striking problems go beyond that. Never mind a close-up look into the whites of the eyes; what will alarm Smith is the view when he steps back to survey the much wider picture. He will see that what was once a flood of Rangers goals has dried to a trickle.

The end of the season is near and Rangers have managed only 54 league goals. When they won the championship just four seasons ago they ended the campaign with 101. The current haul should be improved with five matches remaining but as things stand they are on course for their lowest total in a league season for 17 years.

The team Smith inherited from Paul Le Guen is horribly reliant on Kris Boyd and vulnerable to the consequences of the 23-year-old being lost to any long-term injury.

The spread of goals throughout the squad is paltry. After Boyd, who has weighed in once again with a highly-respectable 25, Rangers' next best scorers are Charlie Adam on 11, Nacho Novo on 10 and Barry Ferguson on six. Prso's own influence has dwindled to just four.

Ferguson's statistic is at the nub of Rangers' problem. In that 2002-03 campaign they swept to a domestic treble with 124 goals in all competitions and Ferguson weighed in with 18, which was a dozen more than he has managed in any other season.

A combination of successful penalties, attacking runs and consistent finishing, which he has not repeated, meant Ferguson was Rangers' second top scorer that season. What was significant about that was that then, unlike today, the competition was intense: Ronald de Boer (with 20), Shota Arveladze (16), Michael Mols (14), Claudio Caniggia (12) and Peter Lovenkrands (12) all contributed.

At the moment Smith will start next season with Boyd, Novo, Filip Sebo, Thomas Buffel and Alan Gow as his forwards.

Novo scored 25 goals in his first full season at Ibrox - it was also Prso's debut campaign and the partnership yielded 46 in total - but then dropped to just three the following year and has never again convinced as a senior striker.

The hapless Sebo has never convinced at all. Sebo has a combination of strength, pace and hunger, and chances have a habit of falling to him. That ought to amount to a potent cocktail, but two goals so far is a pathetic return and he is looking like one of those fateful figures who will rediscover his scoring touch only when he has reinvented himself at another club.

Buffel is a fragile presence in the squad and may also be moved on to free up a wage or act as the makeweight in a deal to land someone else, but if he stays he will not be expected to score heavily and the same may be said for the wide player, Libor Sionko. As for Gow, his touch and creativity for Falkirk this season have been more impressive than his goals total, which stands at just six.

Smith is certain to look at Ferguson's 18-goal return four seasons ago and try to shape the team so that his captain comes close to that total again.

Adam has been valuable but Rangers need a much bigger contribution from their other midfielders even if that will be difficult because neither Brahim Hemdani, Kevin Thomson or Chris Burke score often and Scott Brown, if Smith can successfully land him from Hibs, has a modest career ratio of about one goal in every six appearances.

The fact that Rangers need two different sorts of striker has been evident from the names they have been linked with. Scott McDonald could never be mistaken for a "new Prso" but when Smith made a £450,000 bid on the last day of the January transfer window it highlighted his need to bring in another consistent SPL goalscorer to relieve the pressure on Boyd.

With McDonald now committed to Celtic there is no obvious domestic alternative other than Kilmarnock's Steven Naismith. Smith has denied an interest in the Leeds and Northern Ireland forward David Healy, presumably because his outstanding international statistics disguise a modest return from his years in the Championship.

The one player who would tick all the boxes and compensate for Prso's departure would be Danny Koevermans. The AZ Alkmaar forward - hard-working, able to hold the ball up, strong in the air, a goalscorer, seemingly custom-built for Scottish football - would be ideal were it not for the fact he is unlikely to emulate Jan Vennegoor of Hesselink by leaving Holland for Glasgow.

His Alkmaar team-mate Shota Arveladze has worked as an impressive ambassador for Rangers - eulogising about the attractiveness of the SPL in general and the Ibrox club in particular - but Koevermans believes his game has been improved by working under coach Louis van Gaal and is in no rush to serve under anyone else.

Alkmaar are wealthy and have no need to rush him off the premises for the £5 million or so he would generate. That is more than Rangers could afford in any case, although shifting Prso and goalkeeper Stefan Klos frees a lot of money for them.

Johan Elmander, the Swede wanted by Le Guen last summer, would also be expensive since he has scored consistently since joining Toulouse for £3.5m.

Prso's fellow Croat, Bosko Balaban, would be affordable as he nears the final year of his contract with Bruges but his previous spell in Britain, with Aston Villa, is remembered only for his candidacy as one of that club's poorest ever signings.

Rangers' link with Emile Mpenza - a connection which began in 2000 and resurfaced in 2004 - was rendered irrelevant by yesterday's news that Manchester City are close to converting his current loan agreement into a permanent contract.

Perhaps Celtic's Artur Boruc and Maciej Zurawski could sell their fellow Pole, Grzegorz Rasiak, on a move to Glasgow, although he has scored so regularly that Southampton would not let him go without seeking a sizeable profit on the £3.5m they spent to sign him last summer.

Lee McCulloch may be prised away from Wigan for half that and he submitted a transfer request when the club refused a £750,000 bid from Rangers in January. McCulloch is physical and can play as striker, but he lacks Prso's touch, goal threat and leadership.

Smith must find the men who can find the net. Who will get the goals flowing again for the club that plays the theme from The Dam Busters?