Removing PVA from a CRT

I recently picked up a Rainbow 100. The PVA between the safety glass and the CRT on VR201 that came with it has broken down and failed badly. I have seen videos and read about removing the safety glass, cleaning out the PVA, and reattaching and resealing the safety glass. All that I have seen basically sticks the safety glass on at its edges and leaves a void where the PVA had been. It seems to me that the PVA was providing some implosion protection. Would it work to replace the PVA and attach the safety glass to the tube with an optically clear adhesive sheet? I have seen that this exists, but have never used it before. Also, I have never worked on a CRT before. I am trying to find a local person who can observe me and stop me from doing something stupid. If I can?t find someone, what am I more likely to do wrong? How can I be sure I discharged it before touching it?

and, looking through broken-down PVA, I could see the Rainbow has booted and I could enter DOS commands. I could also see white retrace lines. What is the likely cause of that on a 35-year-old CRT?