Last update:

Both the Teves 20 controllers I have suffered from intermittent ABS light staying on until total failure with code: C1095 Hydraulic Pump Motor Circuit Failure.

I broke one controller open and found bad solder joints on the pins to the pump motor plug, I re-soldered them and it works fine.
So thought I’d just drill a hole in the other unit above the pins (22mm hole saw with no pilot - best done in a pillar drill so you don't go too deep), sure enough same fault, this one’s now working.
I think the problem is that although the board seems firm enough, it’s held in place with mastic. Whereas the pins are fixed in the case so over time, vibration causes the joints to fail.
Check out everything else first as this code is fairly loose - just taking out one of the ABS fuses (can’t remember which) will produce it.

Afraid it doesn’t come apart easily, which is why I drilled a hole in the second unit – in the hope it was the same (maybe common) fault. It’s well & truly glued on with some sort of mastic. There’s a channel all around the base that the cover is glued into. I had to break the plastic all around the base then gradually lever it off with a wide blade. Looks a bit of a mess but you should still have the inner part of the channel left on the base and the lip left on the cover so a decent mastic should still be able to seal it.

First you need to get the locking washers off that go under the mounting screws. Push something pointed into each hole in the washer in turn and lever it up. I used an old pair of pointed tweezers, maybe a dart would do.

The board is covered in soft clear mastic that you have to remove around the pins to inspect the solder but it scrapes off easily with something soft like a matchstick.

If drilling a hole just make sure you don’t go too far, a pillar drill with a depth stop would be best, that way you can use a hole-saw without using the pilot drill.
I used a 22mm hole-saw as it was the largest I had that would stay on the flat surface in the corner of the cover over the pins – keeping on the flat makes it easier to glue something over the hole.

Hope it’s not given anyone false hopes.
I thought if enough people had old dead units they could drill into we could see if it is a common fault.