Prophet 600 voice issue

I’ve recently started working on a friends Prophet 600 that sat in his basement for the past 10+ years. I noticed right off the bat the keyboard needed some work so cleaned it and got the keys working regularly. I also installed the gligli mod which was easy and fixed a lot of issues it was having previously (programs from 01-30 were not working) but then noticed a new thing going on. When I turn it on and give it time to warm up (10-30 mins) I run the tune and notice when it gets to the 6th voice for A, B and F the keyboard only displays 6 and then the letter and then 6 again separately before continuing to the next voice or filters. I also noticed when I play it if I start on a note and play C-D-E-F-G the following note (no matter where) won’t make a sound. If I hit the key again though it works and starts the pattern over. I’m curious if this problem lies with the GliGli modification or if the voice chips are damaged/not working on voice 6.

Any help is great and I am relatively new to refurbishing synths so any troubleshooting tips are appreciated as well!