Thanks for all your helpful responses. So can I summarise?
Shellac is not super strong, separates with heat, and cleans off easily with alcohol
PVA is stronger, best used with a paper interleaf, then separates with impact, and cleans off with boiling water
Loctite (et al) comes in varying strengths and viscosities, separated by heat (hotter than shellac but not enough to destroy temper) but removed with difficulty.
Superglue is similar to Loctite, needs more careful use.
All I need for perfection is a solvent for Loctite and Superglue traces after separation. Acetone? Formaldehyde?
Regards, Tim