Rolling the car in gear would be a better option, but that doesn't look available to you.
Running a prepump will also do the job, even squeezing an outboard bulb wold probably work.
Yes I am referring to starting fluid or gasoline fumes.
You only want to use a
tiny amount, I usually spray one puff across
not into the intake snorkel
while the engine is cranking.
It tends to detonate early, so either disable the glow plugs, or wait 30 sec after the cycle has ended before cranking.
If there is kickback, you used way too much, and can damage rings, pistons, or glow plugs, but there are rigs in my fleet that have started exclusively on spray for 5+ years.
The scenario is the vanes from sitting, or assembly with something thick like vaseline are pushed to the in position and hanging there.
If the starter is good, it will crank the motor at maybe 300 RPM, the pump goes half as fast so it's only seeing 75-150 RPM to fling the vanes into position. If it fires for even a second on spray, and revs to 1000, everything falls into place, and you are good to go from then on.
But...How did the pump look inside? the control collar has to move 100% freely, or you will not be starting.
EDIT:
When I had the solenoid out and in my hand, I energized it with 12v, and the plunger and spring shot out.....I was lucky to find the spring again . No, I didn't reinstall the solenoid without the plunger to try.......yet.
This sounds backward like you might have the wrong kind of solenoid. Energized, a stop solenoid normally pulls in. Could you have switched it with the cold start one (some of which go the other way)?
EAsy test, crank the motor with the solenoid not powered, if you have fuel, plug in the solenoid to kill motor.
Another one of those little crappy filters, or some cheap clear hose on the return line can also be helpful.