Rockola 1454 return b4 playing

Hi
Got another issue with the Rockola , it's started beginning a record but then as soon as it starts it returns the disc to its home slot on the carousel
I have had an issue with sticking pins, this new issue has started since I stripped the top end by removing the gold inspection panels either side of the turntable and examined the pin bank.
I have checked the control box removed it and examined the micro switches etc also checked the micro switches on left of turntable.
My query is there is a pin which is attached to the tone arm assembly and appears to locate onto the grip mech, not sure if this is located correctly, when the record is returned to the carousel the selection mech appears to hurl brtween 2 discs
Any assistance would be great chears