Attempting to eliminate the pool of oil that seems to permanently sit on the cross-member under the back of the gearbox, my first thought was to replace the rear oil seal. This was pretty straightforward, as I’m also in the process of fitting new floors (XK120 OTS) so everything is easily accessible. Blow me down if there wasn’t a fresh small pool of oil in the same place the next morning! Assuming the leak was coming from between the oil seal and the rear housing, I carefully removed it all again and used some high-temp silicone where the seal butts up against the lip on the inside of the housing as I drove it back in. I even checked that the mounting bolts went into blind threads (they do) in case oil was leaking along a bolt or two. Nothing appeared to be coming from the speedo drive area either.
Finally, it dawned on me! Oil is dropping down from the end of one (or more) of the striking rods directly above. I have seen that this subject has been raised on the forum some years ago.
New felt seals are on their way.
It looks like the easiest way to tackle replacing the felts is to take the gearbox top cover off, as well as the gear lever assembly. My question is: are there any tricks I should know about or snags I might encounter? Should the felts be pre-lubricated? Should the new top cover gasket be fitted dry or with some sort of sealant?
I will check that the breather is clear, and at least it will be a chance to have a peek into the box. It is otherwise functioning OK, though there is quite a bit of bearing noise, especially with the clutch pedal depressed.