You must be one of the fortunate ones, Greame. I have two sets of straightened pullers! I have
ALWAYS had to consider doing the drop arm in sitch. Last one we did was the P38 and we took the pump out. Geoff (jnr) clouted the arm that hard that the vice snapped in two. And it wasn't a cheap nasty vice. We ended up getting a replacement pump off ebay.
I have seen it suggested that to get the drop arm loose, slacken the large nut and drive around for a bit!!
It's a character forming task that we all should attempt at some point.
Geoff