Hi Help and advice please.

I have a 1984 500 SL (107) I have owned it for 9 years. When 1st purchased it I had a full service and any faults rectified. However on the 1st long trip the box would not stay in top gear on the auto route/ motorway/freeway. Upon returning found that the gearbox filter had not been changed and had been sucked inton the box. The box was flushed and a new filter fitted which seem ed to cure the problem.

Now 9 years and 2o k miles the car klonks and jolts when shifting into reverse. I have checked the idle which is a steady 700rpm. 1 expert suggest the plates are worn and each jolt bring me nearer to a complte failure and an expensive rebuild !!

Advice and help please