Hi there - please note that I'm sharing what I learned from disassembling a Pentax ME Super in an attempt to fix a stuck mirror. I do not claim to be an expert, and please take what I have presented with a grain of salt. The infinite advance issue is caused by the same jammed mirror mechanism, as I discussed in the "main takeaways" section of the video.
Pentax ME Super cameras (and likely a number of other M-series cameras, as they are mechanically very similar) suffer from a degrading rubber damper in the mirror mechanism that causes jamming of the shutter-mirror trigger linkage. This will likely be an unavoidable development in any ME Super camera's lifetime, and can be difficult to fix without removing the mirror box. However, all things considered, ME Super isn't a particularly difficult camera to disassemble, and requires few specialized tools. If you are unwilling to disassemble the camera to expose the affected pivot, doing a lighter fluid flush or using electronic contact cleaner might help, but it's not guaranteed to work.
For more information, please visit Romping Bronco's Youtube channel. I have not had any interaction or business dealings with him, but his content has been very helpful for diagnosing common issues with the Pentax ME Super. This video was inspired by his three part series on fixing the same issue as I have covered here, and I hope that mine can complement what he has talked about.
