31-23 relates to an internal error with the cassette drive. The un-official solution is to place the cassette inside, and then give it a firm smack to the side of the camera, this frees up the drive mechanism which has got stuck.
Officially the fault is cleared by stripping the camera down, cleaning the mechanical moving parts (i use ptfe\switch cleaner).
The fault is often caused by the missing black roller, but since this has already been replaced it sounds to me like there may be some debris inside causing the issue.
This is a mechanical failure, if you can still see the 'black roller' in place, and cant hear anything rattling around inside \ nothing falls out when you give it a shake upside down, it will need fully stripped down. Which would best be performed by the Sony service centre.
If you provide me your post code I can give you the details of your nearest one.
I would suggest you use DK, they are an approved Sony repair centre and we have had excellent feedback from a number of customer who we have referred to them over the years.
Unfortunately there isnt anyone else nearer, so you will have to post it to Horley, they charge about £60 on average in labour and postal charges to repair, and my guess is the parts wont be overly expensive (maybe £20). If you want to send it to them the best thing to do is book it in via their website https://www.dkavs.co.uk/repair-request-centre
That way you know its being repaired using genuine parts and have a warranty covering the work they do.
Please let me know if you require any further advice.
No problem Eric, appreciate if you can rate the service so I may close the case.