Another word of advice, usually I used to find a dragging clutch was some of the fingers on the pressure plate had gone weak so when you pressed the clutch, the pressure didn't release off the spinner plate fully. Every so often though, I'd find the little ball pivot at the end of the release arm in the bell housing had come loose in the housing. Usually a bit of a beating with a hammer and centre punch to swell the metal and some locktite cured this problem and stopped it coming out again.