Hello,
I, too, had the grinding noise from the starter motor earlier this year and replaced the contacts. That didn't work; the grinding continued and the motor began to stick intermittently. After two call-outs I bit the bullet and replaced the motor. Getting it out is tricky, but this should help:
https://the75andztclub.co.uk/forum/s...d.php?t=325175 The inserted link is also helpful.
Derek.