crockett wrote:

Hi Fastbuck,
Would be interested to know how you get on. Am also in Cornwall, with the same "problem" and a desire to get it fixed - Alpaca phleather with the side split. Good luck, hope it works!

Anyone point me in the direction of a good trimmers in east of england that can do a side bolster (vinyl) replacement?

I found someone to repair mine a while back with the same problem, he is just outside Bedford and he does a number each month.

I can send details if you can not find the thread.

http://www.freel2.com/forum/topic26695.html

I found the thread

Got a NOS leather seat base cover from the LRO show for £30.
There was also someone selling NOS leather seat bases on eBay not so long back for £40 - £60 depending on the colour. I'm sure he will still have some left as he had a good amount of them.
Considering the costs of repairing your old bases, and the fact the seat cover has to come off, surely a NOS seat base is the way to go. They are out there if you look for them.