Glenmore,

Sounds like the pre-engage mechanism on the Starter motor is not retracting quickly enough.

If removing the starter motor is reasonably straightforward, it's certainly a DIY job, only involving a good clean and re-grease of the moving parts.

About as cheap a repair on a MB could be........

__________________
Paul Gibbons
'93 320CE
'73 Jensen Interceptor (Resting)
Giant Full Sus Mountain Bike