Beogram 9500 stops half way???

Hey guys, what might I check as to why my bg9500 stops roughly half way through. It keeps playing but it will not track further so it skips... any ideas? Looking for a spare mmc1-3 also for a good deal.

Thanks in advance.

Hi! Just came across a possible solution: the dust cover is sagging or the felt-strip under the black fixed part has come loose and hinders the tonearm traveling  

I checked those and these do not appear to be the issue. Any other suggestions? Thanks for those as at least that gave me something to check lol.