In that case, the OP should shake it hard in the direction of the hinge?
If the batteries have corroded inside, it may be tricky opening the battery compartment and even trickier removing the old batteries. If he only uses it occasionally, it may be sensible to tape an external battery holder on the outside and bypass teh internal batteries.
I see that someone has one of these on ebay for £150, but there's a mk3 for £8.