Mark

I had no issues during my initial test prints with PLA, but after an ABS print where the chamber was heated for seven hours, the adhesive holding the door handle on has degraded, and instead of opening the door, it tries to lever itself off if not held just so.  It has not improved after cool-down, and I'm likely to need to replace the adhesive.  What's an appropriate bonding material that will survive high temperature prints?

I would leave the adhesive in place (it is messy...) and just add two M3 screws and nuts. There should be pre-drilled matching holes in the handle and door pane, and there are larger holes in the right-hand frame profile to receive the screw heads.

(However, the lower hole is missing from the left frame profile, at least in the early Core Ones. So in case you swapped the hinges to the other side, the screw head might touch the frame, leaving the door seal slightly ajar.)) 

I used this to redo the handle given I had trouble installing it with the supplied tape initially.

I've only done PLA and PETG prints but it is holding up well.