I recently pulled out some old super 8 films and projected them. They were post striped back in the 80s by a company named Aerco. The sound was pretty bad. It keep fading in and out and the volume jumped from low to high. These were silent K40 films that I had striped to record music and narration.
My films that I bought pre-striped (K40 & Exta 160) play just fine.

Has the aerco stripe just degraded over time?

Thanks