I just got a Bridgeport series 1 with a 2J2 head. To move it I tilted the head 60 degrees to the right. The head will now not go back into position. At about 40 degrees it binds up and will not move any farther.
Apply twisting force in the appropriate direction while turning the adjustment screw. 2 man operation.
Then disassemble and clean and reassemble.
Machines require periodic cleaning and maintenance.
The studs that hold it in position may be to blame. If too loose, they can interfere with the housing and get jammed up in the castings. They can also "cam" into the slot inside and prevent it from moving. Try loosening the bolts only enough to get it to move without them having any extra wiggle. If it gets tight, try tapping the studs with a mallet to make sure they are not bound up.