I fiiiiinally got myself together enough to actually phone the motorbike service place near Guildford and ask them stuff. My bike's chain almost certainly needs replacing, along with the sprockets, because it has a few stiff links that, while I thought I'd managed to free them up, still seem to be making it very hard (nigh impossible) to adjust the chain properly. The left fork oil seal has just slightly started leaking so that needs doing, and they suggested replacing both at the same time, which makes sense - both would be around the same age, after all. And the front tyre is near the limit.
The place near Guildford can do all these things, and I've been there before to have tyres replaced (as that seems to be their speciality) (and also they give IAM members a discount) but, once I'd reached the end of my list, the guy did ask how much the bike was worth, presumably with the suggestion that it might actually be better to replace it than get it fixed. And now I don't know what to do.
I don't want to start bike-shopping at this point - I like my SV and have always assumed I'll stick with it until I can afford to switch to an electric motorbike. I don't want to spend lots of money, but I do want to get the bike roadworthy again. Ugh. Maybe I should phone other places and ask them the same things and see if I get different answers. But I also don't want to have to make yet more phone calls. Hmmmm.