Pioneer PL-570 Record Size/Stop Issue

[stargem]

Hello:D My PL-570 plays half way through a 30 -12" record then the arm/needle slides across the record (yikes) and returns to stop like it is set for a 45rpm. The setting is on 12". Anyone had this problem on this model or another?

I also want to check for hard grease and re-lube inside but am relunctant to operate ?? Thanks for any help!!