There are many ways in which the Lightweight gearbox can wear. Don't worry if the components aren't perfect; these gearboxes are simply designed and will usually continue to function well, even when worn.

In the picture, a breather union (visible in the top-right corner) has been fitted to the gearbox casing . This is a modification for racing use, so it can be ignored here.

The layshaft bush is almost always worn oval. It may be so loose that it just falls out; assume you will need to replace this bush.

Later gearboxes may have a hole for a pin to secure the layshaft bush. Check the pin for security or signs of oil leakage. Remove it if in doubt.