Sony vcr model:SLV-M77,year:Aug 1989,has a Sanyo mechanics chassis:

http://www.studiosoundelectronics.com/mbk-31.htm

and the problem is that during playback of a recorded tape on that
machine the audio is intermittent but playback of rental tapes or
tapes recorded on other machines is fine.I noticed that the famous
SCA3.0 cam belt was bad so I replaced it (it was obviously stretched
and would not allow both tape guide posts fully forward so the film
was not at the right height on the audio control head),cleaned the vcr
and cleaned/lubed the capstan motor so the vcr worked great for 1
month and now customer calls back and says problem is back.
I could not find any common repair tips at the free Sony repair tips
programs below:

http://www.orpheuscomputing.com/tech...downloads.html
http://www.moyerelectronics.com
http://intrepid-video.com/techhelp.htm
http://www.schematicsforfree.mattsoft.net/
http://schematicsforfree.mattsoft.net/forum/

maybe because it is a Sanyo chassis.Anyone have any common repair tips
from these pay sites below:

http://www.Euras.com
http://www.winstip.com
http://www.repairhelper.com
http://www.shophelper.com
http://www.circuitwork.com/techassis.../yabb/YaBB.cgi
http://www.network54.com/Forum/27725
http://www.nesda-ohio.com
http://www.anatekcorp.com

or any other pay repair tips site?.Thanks in advance.

Sidney
Dartmouth,Nova Scotia
Canada