If anyone is in need of a fix, I've designed and 3D printed these in a rubber-type filament. Working great so far on my Bongo.
https://www.ebay.co.uk/itm/137033006604

If you still have the vehicle, I sell the solenoids including the converter lockup solenoid, for BM gearboxes..if you have a UM box, I can get parts, but will be a few weeks.

Hi all, I made a new pdf, using the info from the original and added pictures to help users. If interested, its here..

I'm also selling transmission filter and gasket kits, diagnostic test leads and also Full solenoid kits for BM transmissions, including the lock up converter solenoid.

As its a diesel, it doesn't have an engine ecu, per se..use the settings for the auto gearbox and it will give you the codes from the ecu

Oh wow, I'm so glad I found this..I've had exactly the same intermittent problem..started when we were away in Wales luckily it repaired itself to get us home, but it's had me stumped since. Can I ask was it the ecu behind the glove box you changed? I'm guessing that's the only one? WL04189E1A?