Gear box whine and lubrication

[dog-housepaddy]

Hi
Can anyone help me? I have a gear / bearing whine that is most noticable when the engine is cold. It seems noisier in second and third gear but does die down once the car is driven for a while. When I put my foot on the clutch and the revs drop then the noise stops. There is no noise if the engine is running but not being driven. This has only come about in the last 1000miles and the clutch, housing and thrust bearing was changed 5000miles ago.
Is it likely to be the thrust bearing or some other bearing or gear? I would like to check the gearbox oil but I don't know how to find it...any clues? Photos would be nice. I believe its very difficult & fiddly to do...any techniques?
Any thoughts would be appreciated. Thanks

[JensenA]

To gain access to the gear box you have to remove th large alloy plate that is bolted to the underside of the chassis, once this is off you'll be able to see the Gearbox - the oil it uses is ATF.

[brogenville]

I would tend to think that any noise like that that is dirctly linked with putting your foot on the clutch will be your release bearing. As for how long its been in for, well the release bearing on my mx5 started whining less than 10k after being replaced.

[Redmist336]

As brogenville stated it's more than likely thrust bearing.
However you can test further by driving the gearbox and still listening for noise. If you still get noise while rolling and clutch in you could be looking at gearbox bearing issues.