People all over the world are looking for a door seal. Good luck. I sent a door seal that had minor damage to someone in the UK to be used as a mould for a reproduction to be created, I don't remember how that worked out, but I think it proved too expensive.
Are you sure the drum is seized? The drum has a brake, cable operated so that when the door is open, the drum is braked. The brake mechanism is shown in your last photo, 2959. Also the drum only turns one way, that is normal.
Having said that, the drum on mine is sort of seized - it is stiff to turn even with the brake off. Mine is missing the main motor, it was gone when I found the machine.
I did fully restore one of these many years ago, I replaced the drum bearings but they are a weird bearing, thinner than usual and I couldn't find a match anywhere, tried many bearing specialists. I eventually used other bearings of the correct inner and outer diameters but a whisker thicker, I got it to work but it made reassembly really difficult. (I think I had to leave out a spacer or circlip from distant memory...) So if you can make the existing bearings work, try to do that. Of course it would be easier to find a match for the bearings today, my restoration was pre-internet.
Mine was the later one with the round dial, 3226. I also had a 3224 that I got later, actually got a good door boot and the drum assembly was good. That has its own story...
Sad story... I got rid of all my Keymatics when we moved from Melbourne to here, would have been late 1990s. I had the fully restored one, the working one I had converted its mechanicals and electrics to work from 12 Volts DC (we had a very basic solar power system, couldn't run a 240V version) and a few salvaged ones for spare parts. I gave the restored one to the Salvation Army store in Abbotsford to use as a window display, at the time they used to sell some donated washing machines.
The 12V one was a bit nuts, it used a car wiper motor for the tumble action and a golf buggy motor for the spin motor, a car heater fan motor to drive the pump, 12 volt solenoids to operate the water valves and two clockwork timers for the wash and spin timers, it was only semi automatic, not full auto. It did not use the keyplate mechanism or electric timer at all. No heater of course. It was rough as guts to look at but worked well for a couple of years. I tired of it, we had upgraded the solar power system so scrapped that machine and the spare parts machines. Soon after I discovered this website, and learned what a crime I had committed in scrapping them...

One day they were unwanted, common enough, regularly found on hard rubbish collections, suddenly they were rare and appreciated...
After a few years of being Keymatic-less, I found one in hard rubbish. It had already had its motor taken, the wires cut. Other than that, it was in OK condition. That is the one I still have. I have never found a motor for it. I do have a good door seal but I'm keeping that.