I had a despairing look around and I found a wee site called P1Repair.
Found a repair kit, clear instructions – and hey, it was about $12.45US shipped – about £10.
I took the risk and ordered it – on 8 April, as it happens – it arrived in the Scottish Highlands on 15 April.
Got round to it yesterday.
I recommend both the kit, and the supplier if you have a problem with your remote – or indeed anything with a button!
As their website says
P1Repair designs button repair kits for anything with a button. Most new product ideas come from customers like you! Any product that carries some popularity is welcome. Individual buttons are also an option for virtually anything with a rubber button.
I have no connection with the firm, other than being a very satisfied cutomer.