technics SL 7 problem

[101er]

Hello ,I have recently purchased a Technics SL-7 ,
I have just put a new cartridge and stylus I paid $25 (why are some so costly ?? )for it and it sounds fine , it is missing the retaining screws , it works ok up to a point .
There seems to be an intermittant fault whereby the arm will correctly move to the begining of a record , start to play then for no reason return to its rest position and the deck will stop ,
this happens on both 7 and 12" records and at varying places on the record , also when you depress the play button and the deck begins to spin but the arm does not always move to the start of the record its like the arm mechanism is on a secondary take up which doesnt always activate.
So , my question is , is there a remedy \ adjustment ?
I like the styling and size of this deck and would very much like to keep it but not at any cost . Any help would be gratefully recieved .
( as an aside I also own a " the oak " turntable and I would like to get any information on it )
Many thanks .

[elricvanb]

The service manual for the SL-7 can be downloaded from:

http://uk.geocities.com/lineartechnicssl15/index.html

All adjustments are clearly explained; some however, require dismantling and an accurate voltmeter.

Good luck...