Zoom G5: How NOT to fix it! Some lessons learnt from disassembly

In an earlier video on the G5 a viewer asked me questions about the internals. Here's another attempt to clean the buttons and investigate button failure.

NOTE: I add some tips, some "dont do this!" and warnings.
Be especially careful around the tube booster circuit. I have no idea what I am doing here. I managed to buzz the circuit a few times - avoid opening this pedal unless you know what you are doing. My experience here should NOT be taken as any demonstration of expertise on my part! I was learning and wanted to show you some mistakes I made.

TIMELINE

0:00 Zoom G5 disassembly Avoiding pitfalls
0:36 Overview of assembly. Plan of attack
0:47 exterior screws
2:38 removing foot pedal switches
3:04 removing bottom panel. whats inside?
5:45 removing pedal switch PCB
7:31 some footswitches need replacing
8:21 Zoom could have used more screws!
9:31 careful with your nuts!
18:13 PCB closeups
19:35 cleaned board - no diodes
22:10 Jackass testing - avoid this!
30:14 Pedal reassembly
31:06 No fix proposal. Any ideas?
31:29 Final assembly - broken shaft.

Enjoy and do post any hints you managed to derive on fixing these pedals.