Questions to repair a Elmo ST-180E M

[Vale Park]

I bought this projector at an estate sale and ended up deciding to fix it up myself since it powered on. After removing the back panel it was quite clear the belts were molded and wasted away so I purchased a replacement. After installing it actually worked! So I went and bought a 8mm film “Hercules” and after threading it it regrettably started bunching up at the arrow indicator on photo 2. After troubleshooting and doing some research I ended up manually moving the film guide forward a tiny bit and it would thread properly. After some more research I read there’s a linkage for the sound head assembly that can be adjusted at the bottom panel cover to fix this. So this is where I’m stuck.

1.) I tried to adjust this linkage but I’m not sure if I’m doing it properly. As I went to use a torx 6 bit to wiggle it a little the linkage flexed but the socket wouldn’t move. I learned that adjusting this is very sensitive so I didn’t want to do anything aggressive. Also these two sockets so which one should I be moving? And would I be loosening it or tightening it?

2.) Another concern I have is this small spring on photo 3 that seemingly appeared out of nowhere as I was doing all my diagnostics. Does anyone have an idea where it belongs?

[Nantawat Kittiwarakul]

I once had this model (or its close variant, not 100% certain) a while back. Sold it years ago unfortunately. But if my memory is correct yes, that's where you're supposed to set the position of that lower loop former. That metal rod should move along with the upper loop former, and that brass piece set the "stop" position of the lower loop former. Of course I no longer remember the exact procedure to adjust it, but hope this is good enough for you to get going.
BTW I neither have any idea for that spring as well. The safest bet is to open the back cover ans start investigating.