Thanks for all these posts, it's really helpful.  I just acquired a B&L Cinemascope Projector Attachment I and info is scarce at best.  If I can test this one out, I might use it as a replacement for my Isco.  
 
	It appears my copy is completely seized up on the front end.  I might try some 3-in-1 and cross my fingers to get that red ring off...