I mowed the front today with the new oil and it performed its task without complaint. I managed to fit a Victa axle retaining clip to the front axle and made up a shim from a piece of scrap tin as non of the Victa ones would fit. It looks to be effective enough. See pics below.
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!