I don't think blades were ever fitted to service blade holders.
Victa actually did have complete blade holder assemblies [i.e. blade holder factory fitted with blades] available, up to the early 1990s at least, going by the parts lists I have access to.
In fact, along with quite a few of the later blade holder types, the earlier 9C type blade holder wasn't available bare - it came with 9-150 cutter blades fitted, and could also be ordered with side [assembly P/No 9-172] or rear [P/No 9-173] discharge blades fitted too.
My family's OPE shop used to keep a few of the 9C's in stock in the 1970s, for retrofit to Victas that came in for service which still had the 9B holder fitted.
