Hey DuncB!
I thought I'd resurrect your post instead of starting a new one, I hope you don't mind!
I'm new to this forum but have been on AHB for ages (I'm in Melb, Aus). I scored a pump while on a business trip to Manchester in 2014 and by pure luck nabbed two identical units off eBay earlier this year, so I now have 3 of what I believe are all identical EWL pulls like yours but of the 1/4 pint variety.
I'm about to start dismantling them to clean them, and I'm curious, did you manage to open up the cylinder body on yours in the end?
Looks like the bottom unscrews with a big enough shifter but using a strap wrench they seem pretty tight.
Cheers!
Karl.