More details below. Looking for someone to repair this. Any autotrans specialists on here? Prefer someone to do the whole job.
Car is in Cumbria. It drives forward ok!

140,00 miles. Intermittently won't select reverse, just makes grating noise like holding a screwdriver in a flywheel ring gear (as though there is a pawl not quite locking in to a notch). Changed oil - discoloured greyish, not smelly, no big bits on magnetic plug. All other functions seem ok. When it does select reverse it works ok, though just occasionally it will jump out. Used Multiscan to talk to box. No codes. Both solenoids register as working. Reverse shows solenoid A on, D4 shows solenoid B on, D3 B on, 2 A&B on, 1 B on.
Sometimes when it makes the noise and you put it back into Park or Neutral, you can still hear a noise like a rattly shaft still spinning inside the box. Not nice. Cable & linkage etc. seem ok.

The best diagnosis so far is "The box needs to come out and the reverse gear along with the reverse clutches . These are known to fail internally."

If it comes to just the box out & in or a used box swap we can do that, it is the internal surgery I'd rather leave to the specialists.

Peter