Cleaning up/digitizing vhs tapes from mid 80s on

[starbond]

My father passed away some time ago but was a huge amateur VHS guy pretty early on, starting with the Quasar VX system (whoops) and eventually getting a VHS player around the mid 80s. He had about 250 taped-off-tv tapes by the mid 00s when he finally moved on to DVDs. In lieu of a TBC I am using a 1990 Sony SLV-575UC with a passthrough through a Panasonic ES15, into a USB Live2 capture to the computer.

Anyways onto my questions:

I'm pretty sure my dad recorded most of the 80s-mid 90s tapes (the ones I'm most interested in) on a Panasonic PV-1430 Hi-Fi VCR, so many of these tapes have stereo audio recorded onto them but I get some unfortunate buzzing on the audio track unless i switch to mono audio which is considerably less pleasant. Is this truly just a tracking audio error or are these problems baked into the tape so to speak? He has a variety of quality tapes, as you can see, but sadly a chunk of them are recorded in EP mode, which I think further creates problems.
Picture-wise things seem good but every once in a while I get tape where the machine cant auto-detect the speed so it will run too fast, then slow down, then repeat creating an unwatchable picture. The tape itself doesn't seem to be damaged.

I dont plan on digitigizing every tape (200+ tapes at 6hrs per tape...do the math), but he's got many with original commercials and special events recorded that are probably worth saving.


The machine I'm currently using:


The machine these tapes were originally recorded on:


and just some of the tapes