Hey Tezza, re: engine removal from a Model 45, you just undo the nut on the clutch cotter-pin, tap in down to release it from the shaft, and
slide the engine out, you shouldn't have to jimmy it off. You could fracture the clutch half if you tackle it without extra care.

i had to jimmy mine off, even after i released the cotter pin, its not gonna slide of the engine shaft without some 'gentle' persuasion
this is the cotter pin in question
you cant remove it from the clutch untill you reomve the clutch from the shaft.
If the clutch isnt sliding easily, then you will need to apply some force between the clutch and the engine shaft, you will either have to lever it off, or failing that you will have to take to it with a hammer. My clutch was stuck so i had to end up tapping it of with a block of wood and a hammer. No damage done and once its off you can clean it up and it'l slide easily