Thank you ! This has been really helpful and informative especially taking the time to get part numbers etc.
I definitely do not think I would bother spending that kind of money repairing it given the two combined would be close to what I paid for it originally. It’s served us well/had a good life so it will be a case of running it to the ground and replacing as and when.
For now, it works great apart from this gunk but I can see it is reducing so there might be light at the end of the tunnel.
Thanks again for your help/advice!