Almost every time we run into crazy stuff on Tac32 twin telescoping, its the check valves. The elevator sits all night (or for a while), and one of the checks is leaking and there is a tiny air pocket in there and when it gets to floor its shaking or something is not matching up, thus door won't open. You can also try the CAT oil, but if you pour it in the tank it takes a month to get out to the end of the run to have any effect. You can also rub it directly on the piston and pour it into the moat of the jackhead. Schindler or someone used to have a little tool / pump thing that would pump it right in to the bleeder (thus the CAT oil is already in the jacks and not in the tank waiting to be dispersed over time.
Check valves.
