MM3 modchipped playstation only plays SOME backups

I am having trouble with my modded ps1 (scph-5501) that I installed a MM3 chip in myself. Earlier I had hit a sweet spot messing with the voltage of the laser potentiometer(I had almost 100% read rate on all my backups), but then I burned gta 2 and it wouldnt get past a black screen after the second logo screen. So I figured screw it, slightly more power will get me there. a 1/4 turn of the potentiometer later yielded a state where I had maybe a 10% read-rate. then i moved a quarter turn back to where it was and the magic was gone. My sweet spot zone had disappeared. The explanation to this problem with gta 2 is probably simple, the gta 2 burn was just a bad burn and THAT was the problem. The explanation why the sweet zone was gone probably lies within the sensitivity of the potentiometer. Well now I am trying to get back in the sweet spot but I find certain backups play more reliably than others. For example Tekken 3 and Bloody Roar 2 play every time, but castlevania just will not go past a black screen after the second loading screen. This is extremely frustrating after achieving such a successful state earlier. If anybody could weigh in/ share experience/ comment/ or suggest anything on this situation I would appreciate it. I bought a multimeter so I could get an idea where my voltage is so hopefully that will help. will report later. Thank you