[billsheila]

But let me try to answer your questions as briefly as I can:
1) the light is intitially out when gear are in transit (of course) it comes on momentarily when the gear go into the home (but then goes out), the gear doors swing shut and then immediately swing back open. Gear stay up and in their locks, door stay open. Handle doesn't return on its own, but if you manually pull it to centre, then the orange lights comes on steady and bright.
2) micro-switch has been carefully rigged and we don't think that is the problem
3) power pack was the only change but the gear were behaving badly before the pack change (intermittent problems with handle not returning) so I thought it was related to the obvious hydraulic leak at the pack that I was having...which as I said actually turned out to be a line rather than the pack
4) mechanic has used both just the hand pump and a separate mule (no pressure gauge on the mule, but I guess he could rig that up if we need it) during this long saga diagnosis.
5) gear and doors work as advertised on down cycle, either on jacks or in the air (thankfully!)

The description in #1 above is what happens in the air on up cycle. On the ground with both the hand pump or mule it has seemingly worked as advertised. Latest diagnostics have involved disconnecting the doors so they can see what is happening. This has led to the question about whether the main gear are supposed to be hydraulically loaded or not while the doors are in motion and before the handle moves. My understanding is that on these early planes the final handle movement arises from pressure build up after the doors have closed and are "forced" against their stops on the airframe...pressure builds in the "time delay valve" until it rises sufficiently to move the handle.

Personally I am convinced we have a rigging problem with the main gear up switches. They seem to work on the ground but not in the air. Perhaps slipstream air is pushing the switch or the gear or both and we are losing connection. My mechanic is focused on whether something is going wrong within the new (rebuilt) power pack that is hydraulically wrong, which is causing the wacky action of the switch.

I guess I wasn't exactly brief!