I think the general advise is don't try it, leave it to the professionals!
The SL66 is one of the most complex mechanical cameras ever made, and there is a massive difference between unjamming, and fixing it. I'd not even try giving it to a general "all makes all models" repairer, even though I have one who I trust with pretty much everything else. (And indeed, on a suitable camera I'm not adverse to doing the work myself)
Jurgen Kuschnik over in germany is almost certainly the best guy to send it to. His prices aren't cheap, but he will do a good job, turn it around fast and warranty his shutter repairs