Thanks Gwyn & Greg,
And my source once again is the real Mr Elmo, Bill Parsons.
Bill read my problem on here and contacted me by email to say dont send it away yet, he gave me a few things to try which I did, one being to turn the projector in forward with no film, put the volume up high, and spin the flywheel in the normal direction, if it was a fault in the drum area then this pulsing noise would have been present with this test but It wasn't.
Bill talked me through a couple of other possible areas to explore. He was trying to help me avoid having to send the machine through the postal service. As the few possibilities were exhausted Bill said that he had a second hand amp for the SL2 projector within his stock which he knew to be working. While mine is the optical magnetic version, I have no magnetic sound films so I couldn't really care less if my projector was switched over to an optical only machine, after all, 99% of 16mm projectors are optical only. That being the case, Bill offered to send his amp to me to try. Today I fitted it and the machine is now A1 again proving the fault to be within the amp. My faulty one will go back to Bill now to see if he can find the fault but this my not be so easy without the projector, (or A projector) to try it on but there is a few tests he can do.
Once again I have to thank Bill, the master projector technician, for helping me sort a problem which otherwise would have cost me a pretty penny in just postal services alone.
Even in retirement, Bill continues to keep our machines rolling. it isn't just the new releases that keep the hobby going, it's being able to keep the projectors in good working order, without the projectors, the films are useless. I often think it is underestimated what a handful of engineers have done for this hobby, but none more than Bill, even in retirement his wealth of product knowledge and know how is simply outstanding.
When forum member's pat people on the back for copying digital to film for a small fortune, lets please not forget what Bill has done for so many over the years, many of whom have gone onto forums and used his advise they have recieved in conversation and taken the credit themselves, something I would never do. We would have left the hobby years ago when projectors caused us problems, but here we are in 2023 and ALL of our projectors are in pristine condition thanks to Bill. Where else would I have got an amp just to try first? Where would i have got heads for my Sankyo 880, the new film gate for my 1200HD, just to mention a very few items?
It's very good to have a go yourself with the basics but it is most definatly the experience and knowledge that is most important.
Cheers again Bill.