have you tried cleaning the contacts in the switch? just clean the black stuff off the saddle and the terminal in the base of the switch. fine sand paper will clean the saddle, and a small screw drivers blade edge will scratch the terminal clean.

I only say this as my passenger window goes up but wont go down, i clean it out every few weeks and it works for a few days then stops. worth a try i reacon.

We have that trouble from time to time on the BA utes at work, like Troyman said, putting something like ArmorAll or Spraying Silicon Lube onto the felt tracks in the door could help? It does with our Utes.

Or get some vaso onto the runners. My au power windows are sluggish at best, but if i spray silicon spray down the door trims and up and down a few times fixes.

mine works fine from the passengers side but will only go UP from drivers side, and yes it happens often, but yours not working with either is something different i would assume.

Not to poach your post Ash but Lucifa's left mirror won't work
I put a NEW mirror on that I know worked and added a NEW switch and still nothing,
it just stopped working one day, I think I have left door harness troubles
maybe that is your problem? a wire could be touching somewhere?

Less headache too

Leave the BEM alone - sounds more like a wiring issue as you've said.
Drivers window works fine ??
You should test the reg as fitted to the window - this is then subject to normal load. You have power and earth to the door actuators, so a test supply is close by.
Since both switches show the same issue, the problem might lie where the wiring comes together - i.e.into the door loom, probably a connector plug near the left kickpanel.
With the switch up contacts on the front windows - YES.
EB/ED/EF/EL/AU switches are getting old - I'd clean mine once a month.
I use relays now to do the switching, the PW switch assy simply directs lower power to the relay coils - haven't had to clean them for a long time.
Rear windows, which aren't normally used much, usually don't have these problems anywhere as bad.

Yeah, good luck Dude.
Obviously, the internal door loom is common too - might be helpful to run a couple of jumper wires from an outside the door connector in the loom, straight over to the motor plug - only need earth and the up line of course for testing. You can swap wires at the motor to cycle it up and down using the up switches only.

Not sure about being a faulty BEM, but when my blinkers stopped blinking I just changed the little blinker box in the fuse panel and it started working again (this was in an EL though).