Help with r380 gearbox

I've got a discovery series 2. Been having problems with the r380 box.
Very hard to select 3rd from 2nd (sometimes goes straight in)
Reverse gear is relatively easy to select but a real pain to get out of gear, you have to roll back well trying until she pops out. Also I've noticed in 5th gear after about 2 minutes the stick twitchs back into the middle by a good inch but doesn't disengage, not sure if that has anything to do with the problem.


What do you guys think? Bias plate?
New oil?

Thanks in advance.

Worth checking the bias plate for cracking and position also check for worn or loose parts. If ok I would suggest checking the oil level first to see if it is low, if low top up and try again, if not drop the oil to see what condition it is in (any bits in it). Mag plug may be a bit furry but they all seem to do that, make sure you fill up with correct spec oil as 380's are fussy. If that doesn't cure it it may be rebuild time, I'm sure James Martin will be along with expert advice soon.

Turns out my problem was the bush in the yoke had broken away, I found it in the bottom of the box luckily. The ball selector had dropped down and was somehow being held in just by the shaft. Because I didn't catch it earlier enough is damaged the yoke also. So new yoke and bush and probably going to change gear selector ball well I've got It in bits.