Hobie Comptip Mast
I have an 82 hobie 16 and had a comp tip installed by Hobie back when they did this for free thru their designated dealers to try and encourate all owners (particularly regular racers) to switch to the comp tip. Now you have to pay wholesale for a retrofit kit, apparently.
Since the mast cross section is oval it is hard to imagine a properly formed comp tip having misalignment with the sail slot in the mast extrusion. Maybe a little filing of the terminus of the metal sail slot or trimming of the plastic part will solve the problem (if they are not rounded and perfectly aligned you may have an edge that is snagging the bolt rope of the main luff). Consider also whether the sail slot in the aluminum extrusion may have been dinged or smashed up and gotten pinched so that the head of the mainsl cannot feed freely through.
If the slot in the comp tip really is out of alignment and the aluminum extrusion is OK (slot not distorted, pinched, etc) I suppose you might need to get a retrofit kit.