I know the feeling. Back in the day lots of people removed the spitback and made it look easy but mine won't budge either.
Crown 1, 3, 4 have their own coils.
Crown 2, SE1, rafale are interchangeable.
Which base do your coils have. The ones on left in above picture were the last I bought from China with the solid round base.
Strangely enough I've always used these coils for fruits and highly sweetened juice and they are decent but not the best. In the last 3 weeks I've given my crown 1's a rest from their custards and started using the RAF 0.2 coils and theve lasted the whole 3 weeks while when I was using fruits in them 10-14 days was the max.