Faulty switches
If any movement is limited, the cause is likely to be the switch. The contact points inside the switch are at the edge of blades which may not be in contact. Or corrosion can occur at the fixed ends of the blades.
Source: Tee One Topics issue # 9

First, check clean contacts and good greasing (SY)
Certainly can be the fuses - or the switches, or the motors, or...
Neither of the seats in my '69 would move in any direction when I got the car. The first thing I did was CLEAN, well, after disconnecting the battery. I cleaned the fuse panel, removing each fuse, cleaning it and its contacts on the board. I flushed the board with electrical cleaner (Radio Shack); the stuff we used to call 'tuner cleaner' as it was originally designed for TV tuner contacts. I also unplugged all the plugs and flushed them out with cleaner, then reattached. I also repaired a couple of the wire fuses as some PO had just used generic copper wire of a heavier gauge.
Next I cleaned the switches the best I could, with them in place. That is, I didn't open the console (at that time). I placed lots of paper towels under the switches and sprayed tuner cleaner into them, working the switches through all axis until they moved freely in all directions. The passenger switch handle was stuck in one position and wouldn't move at all at first.
From there I moved to the seats themselves. First of all, the seat bottoms just lift out, front first. I spread a plastic garbage bag under the seat to avoid staining the carpets. All the controls are exposed for your cleaning. With degreaser and an old tooth brush, I cleaned away all the dirt, old caked grease and who-knows-what-else from the worms. The worm gears are inside of boxes and I didn't have to disassemble them.
Once everything was clean, I reconnected the battery and actuated the switches. I could tell that one seat's motor was trying hard but with no joy. I pealed back the rubber cover on the motor, just enough to put a blast of thin oil into the bearings and a little grease on the drive gear. I then sprayed the same thin oil into the worm-gear boxes. The parts then moved but slowly.
I continued to lubricate the boxes using the little spray tube on the oil can then smeared grease along the worms. After a while, everything worked loose and I could run the seat worms through their entire range of travel. As I did so, more and more old grease and dirt came out of the boxes. I simply cleaned and lubed the worms after every cycle until they ran clean.
Given the pile of dirt, oil and grease fallen onto the garbage bag, the use for that plastic sheet is obvious. I carefully removed it trashing all the debris and leaving the carpets clean.
Today, both seats work in all directions, if slowly in the case of the driver's seat. I suspect that the motor or its brushes are just worn or there is a resistive connection in the wiring somewhere. Still, the repair worked and the drive mechanisms are clean and lubricated.
Hope this helps.
-rick
Source: The Rolls Royce Forum - England

Removing the switch

Unscrew the centre chrome ring. The inner ring has two small holes in its periphery. You can use pliers in these to unscrew the ring. We found difficulty with this due to the tight space and the angle involved (Grigg Enterprises is making several tubular devices for ring removal.)
Remove the ashtray complete with its matt black box.
Reach in and remove the switch.
Source: Tee One Topics issue # 9

Checking the switch contacts
Remove the paxolin cover from the switch by peeling off the sticky tape.
Examine the blades that have points at the end. If any of these are elevated from the black plastic bars of the switch, proper contact may not be made. To confirm this operate the joystick in all eight directions and observe the points of the operating pair of blades. Both blades should move. If not, contact was not made.
Source: Tee One Topics issue # 9