Gearbox noise

Hi,

I have a gearbox noise on my 225 box, i don't seem to hear when driving but when it's sitting, bring up the revs and it starts to make a noise, put my foot on the clutch, it slows slightly and then goes quiet?

Only does it after it's been driven. Not from cold.

Noise is hard to explain, maybe like a dry bearing at speed?

It has a ttv r26r clutch and flywheel.

Oil is elf nfp?

I'm hoping it's not the mainshaft!

 

Thanks,

Sounds like input shaft bearing which is what I was thinking!