Cause

1) Misalignment between the axis of release bearing and clutch cover causes this problem. Wear on the fulcrum inside of clutch cover along with the wear on lever tips makes less pressure plate lift, results in difficult to disengage gear.
2) Improper direction of release bearing causes one of abnormal wear.

Solution

1) Replace the deteriorated bearing or bush parts. Reinstall a transmission after removal of contamination or scratch on the mating surface of bell housing. Replace the deteriorated release bearing and front cover.
2) Install a release bearing in correct direction.