Some months ago I noticed my car had a sort of droning noise at certain speeds, so I started troubleshooting by aiming at less troublesome parts and climbing up the difficulty ladder:

- Checked my axles and found out that the spider on the right side of the car had a damaged bearing. Problem solved and axles properly assembled.
- Checked my wheel bearings and found out both up front were messed up. All replaced and good to go.
- Drained all transmission fluid (no sign of metallic residue, fluid level was below acceptable) and refilled with Honda MTF.

None solved the problem, although new trans fluid made it a bit quieter. Below are all characteristics of this possible transmission problem:

- Whine that goes WoWoWoWoWo at certain speeds, usually when speed is kept constant. When accelerating fast, the whine can't be heard.
- Noise disappears when throttle is lifted and the car decelerates.
- Noise disappears as soons as clutch is pressed.
- Noise is worse and coupled with a raspy sound when in 3rd (synchro?).

There is also a bonus clicking sound when changing gears, but after trans fluid refill, the clicking sound appears to be fading.

What do you guys think the problem might be? Any advice related to opening the trans?