Hello Stan,
I'm sorry to be late in reply to your question, I have only just seen it. From fading memory now, I recall that the backgear cluster that fits onto the eccentric that is used to swing it into and out of engagement is retained on it's shaft with a broad washer and countersunk screw, fitted to the 'motor' side.
Remove those and slacken the nip bolt that proves an adjustable grip to the shaft in question [to give it some resistance to turning], the shaft should then withdraw towards the tailstock end of the lathe.
I have a new and unused 65 tooth bull wheel available to fit the main spindle, teeth often get broken off those and they are no longer available as spares from Myford. If you need one, send me a personal message (PM)
Good luck with the restoration
Brian