Any Marlin 60 experts?

I have an early 90's Marlin 60 that is constantly jamming. I've replaced the recoil spring, very thoroughly cleaned the gun, oiled it (heavily and lightly), and the thing still jams. What happens is once a shell is ejected, roughly 30% of the time the round that is being fed will go in crooked and the extractors will puncture the case. Rounds eject fine, and when it does feed properly the gun is dead on, but I haven't been through a whole tube (15?) without issue. I've seen stuff discussing the feedthroats wearing out, I have taken it out and gave it a good look over and everything appeared good, nonetheless I polished it with very fine sandpaper, it is smooth as can be with no burrs or divots. The part is cheap enough to replace, but midway and brownells are always out. Any suggestions would be great.

Have you tried different ammunition? Rimfire selfloaders are often picky.

My dad's model 60 does the same thing. His has had several thousand rounds thru it and it must be 30 years old, but recently developed the same problem. A throughout cleaning didn't fix the problem and everything is well polished. I'm ordering the feed throat conversion if it's ever in stock, I also need to get a new breech bolt too. After that, I'll be able to report back.

The high velocity ammo jams more than the standard velocity, but the SV still jams an unacceptable number of times.