I have a marder & just had the same problem. Stripped the engine out & found that the small mount had completely split in 2, the bolt that fixes the mount to the engine had sheared & the grub screws holding said gear had been superglued in place! had to drift the gear off the shaft. When resetting your engine, make sure you position it tight & fix the screws with no loctite. When you are happy that it is good, take the engine mount screw out 1 at a time, loctite & replace. It is worth checking these after every outing as they probably take the most hammering.