Starter motor issues

[Ruurd Schut]

All of a sudden I have problems with the high torque starter motor. During a nice drive this afternoon I noticed that the starter motor ran very slow when starting, just enough to start the engine (3.8; 9:1).
After cooling down outside at my home I wanted to start, nothing happened:
- battery voltage 13.5 V, dropping to 12,8 after a few attempts, remains stable
- starter relais ticks
- sometimes the starter motor comes "alive" but is not able to turn the engine around

At first glance all cabling seems to be OK, no loose connections.
First thing tomorrow is to try with starter cables.

Any ideas / suggestions where to start searching?

[mgcjag]

Check the cables and the main earths.....if still faulty use jumper leads direct to starter....if still not working pull the starter out and open it up...they have large copper contacts inside that wear...but can be repaired/replaced
.Steve