Our boat had a Raytheon 2600 on it when we bought it. When the display began to die we sent the whole rig along with the manual to a second hand marine store in Bellingham. I have no idea if they still have it--- this was several years ago.
We replaced it with a Furuno NavNet VX2. The Raytheon 2600 was a very good radar in its day and while we knew the latest generations of radar were better we figured the 2600 would serve us just fine and so decided not to replace it until it actually failed.
So it did (and we learned the CRTs for this kind of unit are simply no longer made) so we made the decision to get rid of it and get a new unit. Well, we knew the new radars were better but we had no idea how much better until we actually got one.
So having operated a boat for a number of years with a 2600, all I can offer is that if you use your radar a fair amount and you can afford to upgrade to a new-generation unit like a Furuno, do it. The difference is not just amazing, it's staggering.
Just two examples--- the old 2600 had a minimum range of (IIRC) 3 miles. Or maybe it was 1.5 miles, I don't remember. But the Furuno has a minimum range of 0.125 miles, which mean in our waters we can pull the range in to spot crab pot buoys out in front of the boat.
And the 2600 required a hood to view the display in the daytime. So only one person could look through it. Today's radars have bright LCD screens that don't require a hood which means that both my wife and I can see the radar display when we are using it in poor visibility like fog. And two pairs of eyes looking at stuff like this can often be better than one.