Originally Posted by Sid Squid

Remove the lever again and locate the split in the fibre bush on the inner surface of the lever, now very very carefully roll the bush up a bit and remove it from the lever. The inner surface of the lever will have some corrosion on it, which expands and makes the bush grip the pivot, file/scrape/whatever the corrosion away and grease the inner surface of the lever and refit the bush, check it turns freely on the pivot before re-assembling.

Be careful with the bush - it's not supplied separately.