I wonder if there is a chemical process to dissolve the remnant adhesive on the glass. because the razor method seems like a pain in the ass and can go incredibly wrong if you slip and hit a ribbon.
I would also fathom that is part of the reason the LCs and other machines are shielded, is to help with EMI produced by the HDD, FDD and PSU which could radiate into the monitor and introduce wobbling.
Also two CRTS side-by-side will do the exact same thing.
Make sure the monitor isnt near any alternating magnetic fields/EMI sources, ive occasionally found fans, transformers, and other nearby objects to cause CRTs to wobble.
Is this a miniscribe drive? I have seen the write amps fail on these drives in the past. Entirely possible thats what happened. The head isnt getting the write current from the write amplifier IC.
The UV produced from the bulb itself will accelerate this.
It might be possible to retrobrite, or vaporbrite, but it would probably re-yellow with time.
Ive never personally ran into it before, at least not yet but just looking at the pictures I can map the circuit out in my head pretty much right away and see whats going on, luckily.
yeah Q4 is the high-side VCC switch for IC3. Whatever happened with IC3 blows Q4.
Q4 and Q9 are NOT zener diodes! They are transistors.
Q9 shorts CN3 1 and 3 together when enabled. R48 is a pullup to keep the transistor turned OFF when not asserted by the control circuitry.