Jonas
Your distributor is fully made by Crosthwaite & Gardiner & they changed the shaft & bearing design to have a ball race at the top of the shaft & a needle roller at the bottom, the Lucas design uses plain Oilite bushes, Martin Jay has looked into changing the bush to a needle roller bearing but due to the shaft diameter has not found suitable bearings.
Martin believes as the Oilite bushes are full length it gives adequate support to the shaft in this application, so does not believe a change is necessary.
One of the problems using roller & ball race bearings is lubrication which does not exist in this application as the distributor runs without any oil supply! Oilite bushes on the other hand are impregnated with oil as it is a sintered bush, I am sure Lucas did extensive wear rate life tests when they designed the distributor & found this plain bearing design works!
One would expect shaft wear over time with the oilite bush design, but clearly it works!
I suggest you contact Crosthwaite & have them repair the distributor, i doubt Martin would wish to repair it as i would expect it would fail again!
Robin
