Today I was able to pull the rocker and low and behold! A broken spring! I was able to pop the old one out and put in the new one from our host in 15 minutes! The keepers even cooperated thoroughly! Engine is running smoothly, quiet and there is a noticeable return of power!
Thanks so much for the keen ear Ivan and to everyone who posted advice!
Side note: when I ordered the spring, I also ordered the Kirk Engines Valve Tool and it blew my mind! Best tool I've ever used and was able to set and check clearance on the 1,2,3 intakes in under 5 minutes. I highly recommend it.
