SV650 (Curvy) Ignition issues

[LyokoBSTN]

Hey guys, so thought I'd see if I can't pick someones brain on here, as mines getting pretty dry on trouble shooting here.

Now down to it. I have a 2000 reg Suzuki SV650s. Rides a treat when she works correctly.
Now a short while ago I had an issue (After a ride in particularly heavy rain) where the rear cylinder was cutting out (Then coming back on after a very short time). This was off putting to say the least, and made me worry I could be damaging the bike, so I got the bike home and garaged her up.
I came back to start her up after a day, and the rear cylinder had totally given up. Now between it happening and now, I'v checked (And replaced) the most likely causes that are cheapish to do.
I started with the spark plugs, but that had no effect, and the cylinder didn't want to know (at this point I hadn't pinpointed it down to the rear cylinder). So I looked into it to try figuring out what was going on. Checked the rear HT lead to see if it would spark. When I initially did the check, I got a nice spark, but then, swapping the spark plugs over, I got nothing. So I thought it was odd. After a little more time, I got no sparking what so ever though. I thought it could have been the rear Ignition coil, so I got a second hand one that was off of a working SV from a dealer in Southampton, Swapped it out, and still nothing.
Now to what action I did today. A friend of mine (With a much better knowledge of checking electrical circuits) came over with a multi-metre, and checked the different points in the system. From the readings he was finding, it appears that the Ignition coils all had the same reading off of them (Including the front one which I know works). But also the wiring leading from the rear coil had no issues either.

So, here is my question to you guys. What could there be to check?
I'm going to do a function test tomorrow (Weather permitting) to see if the rear coil is working for certain.

So Yeah, anything you guys could recommend would be great.

If you have read this far I thank you, it's a long read, but I wanted to make sure I got the full story of what is happening with my bike across, to maximise the chance of someone knowing what is wrong with it.

Cheers guys.

[Pigeon]

If the wiring from the coil is ok, what about the coil itself, or it's contacts.

Not sure about the rear, but the front cylinder has a small drain hole which can get bunged up causing the cylinder to potentially fill with water.
Probably not the issue however as you've replaced the plugs, but it's not always easy to see......scrap that, the rear is very easy to see down.

[LyokoBSTN]

Yeah, I saw about the drain hole, and checked/cleared it just in-case (This was before I figured that it was the rear that isn't firing)
As far as I know the coils themselves are fine, though having had a chat with a family friend who was a motorcycle mechanic, he said to pull the spark plug cap off the HT lead and check the lead for a spark direct off of that.

It's pretty much a case of nothing coming from the rear spark plug (Checking it by pulling the HT lead out, plugging a spare plug in, putting to the cylinder head, and turning the bike over)

As far as I can tell, from the spark plug, back to the Ignition Control unit seems to be working fine (Haven't checked the control unit itself though.

[doggone]

I'd suspect the secondhand coil is dodgy.
To be fair it might have been banged about in transit and tested OK when sent.
They are both the same so try swapping yours over to test.