The sump gasket has to be removed to sort out an oil leak so seemed a good idea to check out the crankshaft thrust bearings. I measured about a 6 thou free play with feeler gauges which is ok (ideally 4 – 5 thou) so i replaced the bearings with new. Previous owner had checked mains and big ends and all ok – although noted the crankshaft has had a 10 thou regrind at some stage. Generally all looked ok.