Luckily I remembered that Cameramatiks in Edinburgh does on-site repairs. Took my #Vivitar28mm in, it disappeared round the back, tap tap tap, reappeared, all fixed. No charge, a smile and a little talk about not cross-threading filter holders!
So relieved I bought a roll of #Scala and a couple of rolls of an #Adox ISO 50 film in 135 for around £8 a roll!
They also has a #Pentax ESII in for £299. With fond memories of my Electro Spotmatic, I was quite tempted... not this time!
@kaiser_photo Thanks. Making the trichromes has a bunch of seps, starting from making sure you always use the filters in the same order, so you know which frame is which. It's quite tricky to map the photos to colour channels in Affinity Photo, though I believe it might be easier in PS.
This is one case where I will happily use a tripod!