Cheers guys.
The 10uF 'greencap' I found was $11 in store, and enormous, so I did the normal thing and grabbed a 10uF NP electrolytic - the model in store was of a different brand to the one I just pulled (C505) so I thought it was worth a shot. I did grab a couple of 22uF Low ESR caps just in case someone thought it was wise to try out (something like 50c each) if the NP didn't pan out.
If none of them can survive, I'll order a better part and wait.
I compared another mono monitor I have open, found it's equivilent C505. It uses a 4.7uF NP electrolytic (I know it's original becasue I unboxed it two weeks ago) - made in the same year, and it's 4.7uF cap is as big as the circle drawn on my PCB. I'm not sure if this is just "technology improving" or if it was larger for an engineering reason (like heat). Further confirms C505 was replaced - will be interesting to see how it's similarly sized replacement deals with it.
For the 2.2uF caps, I found the originals were marked +/- 5% and still in their value range, so I plan to reuse them to start with because I think the replacements I grabbed are possibly worse (and I could just be creating a new issue by fitting them).
Turns out my $1 scope works (Advance Instruments OS250TV - 10Mhz dual channel CRO), so grabbed a set of 1x/10x probes - calibrated it using the built in square wave - and I should be able to post more interesting/informative results if replacing C505 doesn't do the trick. (absolutely amazed it works)
Still no ESR meter, but I'll take care of that soon.
Busy weekend but will try and make time to get it powered up tonight/tomorrow.