Sounds like you are seeing a feature instead of a bug.
The 727 has hydraulically operated surfaces, so they at least become very heavy when you don't have a system powering the hydraulics.

There are engine driven pumps (2, on engine 1+2) and some electrical driven ones (3), powering two systems, A (Engine driven) and B (electrical driven) which at some parts overlap, at others are separated unless forced to be interconnected. The standby system uses one separate electrical pump.
See the above colours to take a glimpse. Pure orange means "B" and pure blue means "A" while the mixture means that both systems power that surface/system.

Want to operate the gear in the air with your engines failed? Well, see where the gear is "located" hydraulically. You have to interconnect there or you don't have any hydraulic power available.
The whole left part of the blue system "A"  isn't powered if you lose your engine driven pumps, so that interconnect switch gains attraction in regard to the situation you are in.

There e. g. is this buddy to warn you about low pressure in some vital systems.


On the ground, for all the surface related movement the engines must run or you have to use the electrical driven pumps which are 9 and 11 in this screenshot.
Switch 18 connects the two circuits if necessary, so the electrical system B stuff can pressurize the system A circuit. That switch may be your friend in emergencies.


So if you need some "System A" movement without the engines running, you have to get electrical power from external sources or the APU, you have to enable the electrical system B pumps and you have to connect the system B to system A then.

Thanks for the nice reply!