Sound problems in TSS

I'll start by saying yes, this is a boot but no, I don't think that's the problem since I never had this problem on my 1 or 2-slot boards. I even verified again last night on an MV-1C and it works just fine. This only happens on my 4-slot. I have cleaned the contacts with alcohol and an eraser.

Basically, half way through a round, the music cuts out (earlier if there's a lot of action on the screen). When the round is over, the music comes back (the between-round music) and plays for a bit into the next round then cuts out again. If I play long enough, the effects may cut out as well and when that happens, the music doesn't come back. If I play even longer, the effects may come back but the music still doesn't.

The music tracks play through just fine in the Universe Bios jukebox mode.

No other games have any major problems like this (currently have Neo Turf Masters, TSS, Bust-A-Move Again, and ROTD installed).

Any ideas?

This happens to me with a Puzzle Bobble boot I have, but on an MV-1FZS unit. Sometimes what I'll do is just pull the cartridge out, give it some hearty blows with the heel of my hand (on the carpet so as not to dent/break anything) and plug it back in and then it'll work just fine. Don't know what else to say really.