I know nothing about magnetos and how to dismantle, but if the condenser fitted inside is so difficult to replace would it be worth removing from inside the mag and fitting an easy cap condenser?
Absolutely it would, and well worth doing.
To fit the Easycap properly you need to do a condensectomy to remove the old cap (unless you kwow that the original failed 'open circuit) although more commonly are just leaky when hot.
https://library.brightsparkmagnetos.com/condensectomy/printer%20friendly%20version.htm
I've done it on two MO1 magnetos, one without full strip before I had a magneto bearing puller and this was quite fiddly. Being able to pull the bearings and strip out the old capacitor was much easier.