I just wrote a very long detailed and rambling account of tonight's spannerings, but it didn't post successfully and the back button didn't recover it :(

Here are the key points:

Cleaned the holes in the caliper bracket and greased the bolts and put the caliper back in place. Back wheel turns fine. Caliper moves smoothly without pads in and moves a slight amount with them in.

The disc appears to be thick enough - (no vernier calipers to check, but the most accurate measurement I could get shows) 4.8/4.9 mm, and the minimum is 4.5.

The pad appears okay -a fair bit of life left- but there is a scuff/gouge in the surface of one of the pads. I can't imagine this could completely stop it working though?

Both pads and discs are OE, with 20K miles on them. I'd say my riding style makes "average" use of them.

One of the 5 inner bits of the disc (don't know the technical term) where it's mounted is scuffed as though the caliper bracket has caught it at some stage.

A test ride showed the same as yesterday.

I re-bled the brakes. No air came out when the bleed nipple was open and the pedal was being depressed. Worryingly though, despite a very snug fit of the tubing (using the "half full jam jar" method) some air appeared to be getting in at the top of the tube, around the bleed nipple (this happened even when the bleed nipple was closed- so it's not coming out of the caliper). To stop this air getting into the caliper, I closed the bleed nipple each time before the pedal was fully depressed and no air came out of the caliper at any time. In spite of this, firmness improved only marginally and I couldn't get it properly firm. I should mention the brake fluid used today isn't brand new; it's from the same bottle I opened (from new at that time) 2 days ago. In the interim, the lid was kept on. Is this okay?

Am I right in thinking if air was getting in, surely fluid would have to be coming out? I can't find any trace of any leak.

A post bleed test ride showed the same as earlier.

I've left the bike with clean kitchen towels all along the brake line and with the pedal depressed in the hope that any leak will be apparent in the morning. Likewise, if it's just airation, it may work its way out. Should I do this with the resevoir lid/seal on or off, or doesn't it matter? I'm clutching at straws though and don't think it'll be any different. :?

As ever, thank you in advance for any suggestions on what to try! :cheers:

I've had that here and on other forums in which I participate. Usually it's a time-out that causes the data to be lost, so when I click Submit, I always quickly select-all in the text box where I typed everything and press Ctrl-C. Then, if the page fails, I can always paste it in on another attempt. Takes no extra time, because I'm already waiting for the forum server to process the page anyway.

Just a habit that's saved me some time.

I actually did that with the second time I posted it. It was part of the reason for the accidental secon post. :oops: :)

Ta for the tip though- I will do it religiously in future.

Update:

I checked it again today and there is no more firmness than yesterday. I couldn't see any evidence of a leak (on the paper towels I put down) other than a tiny dot of brake fluid (which may well have been there before- it was on the back of a bit of pipe and I could have just missed it when cleaning it all). Also, where it occurred was above the cylinder (bit of pipe below the resevoir), so am I right in thinking that all a slight loss of fluid there would do would be to lower the fluid level slightly?

I'm going to book it into the garage tomorrow. :(