That frame rail can snap in place. Align it and press firm. I would not glue as it must come out later if shell needs to come off. Usually the issue is they are hard to get out:-)
When using DCS Remote Commander, you need to turn smoke off before applying power. Normally, smoke and volume off is CCW. Then put on track and apply power. The Engine will read the setting of the smoke and volume switch and use those settings. Sounds like you finally got it. Once you make a setting change you do need to wait at least a minute before trying again. The processor can still have power and be running with previous settings. If you apply power too early, it won't use the new settings you did.
There was an issue with early PS-3 that the smoke unit would still run at a low volume, but that was fixed with new flash code.
As far as Cab Light, the PS-2 RS-3 I have worked on did not have one, Either take the shell off, or take the advice of those that have one.
As far as warranty work, I do not mind doing it for my customer, but in general I do not other than warrantying my work and parts. When your really busy doing a job for nothing, and creating a back log for billable customers does not make sense. Helping your own customer always makes sense
MTH warranty turn around is pretty good right now, plus if your into cosmetic issues they are the only ones that can get it done right. They have access to the parts that are in the pit and not placed in the computer system. A NASC and ASC are at a disadvantage. So it would take much longer to get fixed, especially if parts not stocked. G