Those tilt assist mechanisms are something I deal with all the time. They are almost 100% of the time with a broken cable. The cable is supposed to release pressure on the cylinder so you can actuate it up or down, but usually where it connects at the cylinder or the lever is snapped.

FYI dont ever flip that lever on a working unit if the motor isnt on a work stand or boat mounted (IE lying on a pallet or hanging from the lifting eyelet). If it is working the stern bracket will tilt up and you wont have much luck trying to fold it back down to put the motor on a boat! Makes for a very challenging installtion at 75 degree tilt!

My advice is turn the release screw (flat head) which is down near the bottom of the nitrous cylinder so you can move the motor freely without the cylinder being active. Basically you just have no tilt assist.

Buying one of those cables is around $200.00 if memory serves correct then good luck getting it reinstalled depending on condition of the original components.

Conversely on these motors, despite what the service books say, if you find a working unit slipping the stern bracket off and replacing is pretty easy if you can find a working replacement. Just pull the lower stern bracket mounting plates off (3 screws I believe, with two clamshell pieces), take a crow bar and pry the bottom swivel tube away from the exhaust housing about a 1/2 inch and slide the whole assembly off. Then repeat for installtion and you’re done. I believe this can be done with the older pre 1989 models too, but not on any of the other bigger or smaller sized HP motors. The rest of them dont have enough space between the upper swivel mounts and lower cowel to push the lower swivel bracket away from the exhaust housing for clearance, at least, not without loosening up the lower cowel/pan.

Like Dan said, FLEETWIN can chime in a wealth of knowledge related to these motors and probably correct any ommisions I may have left or screwed up!