Eventually my mate splashed out on some new strings and we took the old ones off the Marlin, but the back of the bridge was still too high - On slackening the six screws at the front of the bridge, the back of the bridge dropped to it's proper position - without stripping it anymore a small block of wood was wedged into the gap in the back of the guitar such that the bridge couldn't move - then the six screws were re- tightened.
after re - stringing we were then able to set up the action and the intonation - I know it's not the ideal solution but now the guitar is well playable although there is no tremelo arm at present.

Anyone know where I can find Bridge springs for a Marlin ? - Strat springs might fit, I don't know if Marlins are still in manufacture ?