Canon New F1 problem.

I shot a couple rolls of HP5+ today and towards the end of the last roll my ears were telling me the shutter sounded slow, maybe my imagination as my hearing falls off at high frequencies pretty fast.
After I rewound the last roll I started stepping through the shutter speeds and after a few clicks it hung up. The iris was stopped down and nothing I did would clear the malfunction, new battery, tried the stop down button, cussed it a few times...all to no avail. When I took the lens off it appears to be stuck mid shot with the mirror in the halfway position.
Any ideas or should I leave this one to the pros?

Time for Ken Oikawa.

Well, I fixed it myself.
I continued to search for my problem on the web and came across a very similar problem. at this website https://www.photo.net/discuss/threads/canon-f1n-slow-mirror-fix.485856/
I had attached a QD plate to the camera today and cranked it on pretty tight and it appears I had ever so slightly deformed the bottom plate enough to interfere with the mirror mechanism as shown in the above link. When I removed the bottom plate I was able to see a very slight drag mark on the inside and just touching the mirror mechanism released it. The camera now appears to function properly again.
I had sent it in to United Camera Repair for a repair and CLA less than 2 years ago and it had been an absolute joy to use since then I suspect it will continue to be.
Weather permitting I will run a roll of film through it tomorrow to verify.

Mackinaw, thanks for the suggestion though.

Some 1/4 Whitworth tripod screws have a nut on them so one can limit how deep the screw penetrates the camera base plate to avoid this problem.

I think it was more a case of the QD plate spreading the contact to a wide enough area to cause the hang up.