Weak red signal (presumably)

[Vertigo]

Aloha!
Recently my super gun's red signal weakened and now there's definitely red there, but it's more brown than red. The other colours are definitely correct, I get everything else fine, but anything involving red looks brown, which makes Samurai Spirits look a bit silly, among other things.
Where should I be looking to rectify this? Presumable it's just a weak signal coming from somewhere, but I don't know where to look and don't want to flow the solder along all possible red signal points, unless anyone has any better ideas.
It does it on different games, both MVS and standalone PCB, so it's definitely not the signal coming from a particular board or the MVS, and it's not coming from my telly either.
I don't have colour pots on my super gun so can't easily adjust that way and if I did I would be wary of overdriving the red beam anyway.
What's the point of a good, clear pixel if it's the wrong colour?
Anyone?

[blackevilweredragon]

red looking brown..  you using NTSC?  this sounds more like a chroma issue more than a red issue...

[Vertigo]

RGB via SCART m'dear.
And yes, it is outputting RGB, my TV says so and so do my eyes, there's no shimmer there at all and my super gun doesn't output anything else.

Edit: Doing some unscientific pics now to demonstrate.
Edit2: Unable to do pics to demonstrate as colour differences are too great between TV and emulator to demonstrate properly. Suffice to to say though, my reds are more brown than red.

[blackevilweredragon]

Huh..  I swear, brownish colors for red is weird, as that means red would have to be dim, but green would have to be emitting when it shouldn't..

By any chance, (and i swear this shouldn't happen), but, did you mess with a hue/tint control that has modification abilities for RGB?  For example, my HDTV accepts RGB, but it allows modifying the hue...

That's the only way something like this happening, seems possible, to me..

[Vertigo]

Nope, can't modify tint on my TV without a NTSC signal going in.
Can modify colour, but doing that doesn't seem to affect this problem, it just makes the browny-red more browny-red
Other colours are slightly affected by it, obviously, but the brownness is not a result of a weak blue or green, or doesn't appear to be anyway. Wardner is still very green and blue things like sky and sea are still very blue.

And no, before anyone says it, I'm not comparing my TV to an emulator and wondering why the colours don't match.

[viletim]

When are you going to open up this super gun and tell us what's inside?  

[Vertigo]

There's nowt inside but wires and a fingerboard to keep track of it all.
And an ATX PC PSU.  

[patch6]

The red CRT gun might be dying. You might have to open the monitor up and fiddle with the potentiometers on the board attached to the CRT to manually calibrate the color. There are varying numbers of them, so mark the starting positions of them and tweak them carefully to find out which is which, while comparing a test pattern displayed by the faulty monitor with one displayed by a properly functioning one.

Finding a guide for that calibration would be strongly recommended. I don't remember any of them offhand, though.