Thanks chaps, I appreciate all the input! In leaky roof news, I fitted that hardtop which has cured the leaking at the sides but I always knew the windscreen seal wasn't fantastic as it had a little lump where it wasn't sealed properly. I just lifted it slightly to see how bad it was and the whole seal came out easily. Very poorly fitted. Tonight's job is to whack a load of RTV in there and seal it up, which should mean bone dry interior from then on!
Sorry, I didnt realise this was a push bike forum. Easy mistake to make. I have no where near the balance and skill to ride a trials push bike. but find it fascinating to watch. Anyway, ride safe everyone
I can only really repeat what Adam said. It sounds a lot like the symptoms you get from your battery terminals being loose. Check they're tight and that the battery's earth strap is in good condition. Failing that, maybe check the engine's earth strap. I've had to pull the Porsche's gearbox out to attack a bolt that snapped when I was taking the mounts off to fill them with polyurethane. On the bright side, it's let me pull the gear linkage out as it was hilariously warn out, leading to an impressively floppy gear stick. It'll all be getting replaced with rose joints, and I'll extend the gear stick and slightly reduce the fore/aft throw while I'm at it. If all goes to plan it should make it a little nicer to drive. Oh, and this is an impressively slow responce, but Paul, the Saab wheels I bought are the same as these (but a little less mint):