Gearbox leak

[Sportw]

The gearbox works well but leaks, seams like the seal is bad on the box, is there an easy fix I.e. tighten bolts or how long and how hard is it to change the gasket seal for whole box time and cost
and should I lthink about a rebuild whilst I'm at it?

 

[Coops Mk1]

Where's it leaking from??

 

[Sportw]

Where's it leaking from??

Leaking from the bottom near the selector but not on it as I know they deteriorate