Have had a US 2600 for a few years now.
I bought it originally in the mistaken belief I could use it with my CRT in the UK with an RF connection. My plan was to use it with my Harmony cart loaded with a full ROM set and then make a small collection of CIB copies of my favourites.
It's a 4 switch woody and when it arrived it wasn't in as nice a condition as described. It's OK - just not great. The switches were pretty seized up. The difficulty switches at the back were jammed - got one working and one snapped off. I can still adjust it with a screwdriver but it needs replaced. Its the P2 switch so will be rarely used - but still - I was pretty pissed off.
I complained on eBay and I got a refund to almost the full value.
So when I realised the UK TV tuners wouldn't pick it up I got it modded for composite. Bought a kit online and got a local electronics repair shop to do the mod.
Got that done and got a really nice clean picture - but - only in b&w. The instructions with the kit stated there was a colour pot to adjust but it didn't seem to make any difference.
Bought a composite NTSC - PAL converter. Didn't work.
Tried it with several TVs , modern - even a projector - nothing. Still black and white.
So I put it away. The idea was to make it a project. Learn to solder - replace the diff switch and maybe recap it if that would sort the colour problem.
Lay for a 3-4 years.
Recently got a couple of "new" CRTs after my old one died. Thought maybe I'd try again.
Rigged it up - still b&w.
Opened it up and tweaked the colour pot again - and - colour!!!!!!!
But there is some interference on the image - diagonal stripes. Seems to be affected by sounds too. It's not a huge deal - is more noticable on certain games than others. Still would likeit sorted.
After some poking around on forums - it seems to be an interference thing - poor shielding on cables - and some power supplies can cause it.
The power supply is pretty old and the cables I'm using are cheap so I'm going to try that out.
I also have a 6 switch woody PAL unit with an RF connection that gives me a sweet image on my CRT. I have a pile of PAL60 ROMs of my favourite games on the Harmony so I always have that as a backup.
If I sort the interference out I may consider replacing the diff switch.
Just thought I'd post here and update from time to time.
May start posting more about some hidden gems I find in the huge NTSC ROM archive I have.