sounds like maybe the autostop is triggering when it shouldn’t. i had a similar problem on a full size cassette deck but i never actually found out what caused it specifically. i just kept cleaning everything until eventually it worked correctly. MAYBE there’s a tried spring somewhere that’s finding resistance where there isn’t any?

it sucks that everything looks like it should work, but it’s doubly annoying that the problems are happening on a walkman. at least on a desktop cassette deck you can easily tear it down to parts and watch everything work in realtime. that’s a bit of an ask for anything miniaturized 😄