Hi,I'm just about to take the shaft out, both shafts get a drop of oil before sailing, one runs hot, the other is fine, something is amiss!. I will check for polishing /scoring/and if it is bent. Thanks for the pointers. John.

No problem. How much oil do you run in the tubes? are they full or just "lubed occaisionally", other thing to consider, if you say the tubes are hot to the touch, is the motor end bearing bush, increasing in size with the heat and pinching the drive shaft and this is what you are sensing as a vibration? you should be able to tell more when you pull the inner drive shaft out and inspect it, see if you can see any polish marks on it, then you can relate it to where the problem lies.

Thanks for the advice, I'll take the shaft out and see. I'm sure I saw somewhere, a rigid coupling for this job, but cant find anything at the moment.....The props are nylon, so no problems there....the top of the tube gets quite warm after a run even with oil...! Thanks again, John.

You can simply use a piece of brass tube, to slide over the motor shaft and propshaft for example, to allow you to get both items in alignment.
Incidentally, have you checked the propeller? has this been damaged and one of the blades bent over by mistake?

it is always better to pull the inner shaft out and roll it on a flat surface first though, to make sure the actual shaft is not bent, before you go further....