Ok so stuck some power to it and sure enough, it was still poorly sick n dieing. . . . Kicking it didn't work.!

So after further investigation and checking out the price of Fadal replacement cards it soon became apparent it wasn't worth sticking with the original control.
Apart from the fact parts are expensive and difficult to find in the UK it's also limited in Memory for running G-code generated by modern Cam. It could be made to do so by drip-feeding or adding USB etc but this all adds up and still got old control.

Now the question is what to replace it with.? and what to replace.?

The machine uses DC brushed Motors with Resolvers and AMC Amps, which all work fine and good quality units. However, I've decided to replace these with AC brushless servos and Modern Servo drives. The reason for this is simply to bring all up to modern standards that are readily available. The drives and resolvers for these old motors are getting harder to find and very expensive when found. Also, I can sell the old ones which will go a long way to AC servos or even cover the costs completely depending on what I use.!

Doing this also simplifies things in lots of ways.??? . . . Why the question marks, well there's a twist to the decision.!
Modern drives mean I can use Step n Dir controller rather than Analog if I like which will make things a little easier come set up time. The twist is that I want to use the 4th Axis which uses Brushed DC motor with resolver and the drives require Analog.!

So my options get a little more limited unless I change the 4th axis motor as well which I'm not so sure is easy to do. Need to check it out.!
The 4th Axis is high-quality Japanese Nikken unit which is also worth lot of money so possibility I might sell it.? . . . Not sure how much I need a 4th axis.!
I also have to consider the Resale value it will add to the machine compared to how much it's worth if sell it on its own.? Could shoot my self in the foot because there's a high probability I'll sell this machine when it's finished and could add a lot more value and salability to machine than the individual resale value of the 4th axis.?

To keep the 4th Axis without changing motors leaves me very few choices because the controller will need to mix Step & dir with Analog and be able to handle resolvers rather than encoders.!

Basically it boils down to just two, LinuxCNC with Mesa cards or Dynamotions Klop, even then I'm not sure the Kflop can use resolvers and requires encoders.? It is a possibility I can just change the Resolver for encoder on the 4th axis which I don't think will be too difficult. Need to check both out more.!

If I drop the 4th Axis then I can pretty much use whatever I like. However, this machine deserves a little better than just being closed loop back to the drives, so I want the loop closed back to the controller as well.
This rules out some of the weaker and cheaper options like Mach3/4 or UCcnc unless I go Analog, even then it doesn't come cheap and is less than ideal.

So I'm back to LinuxCnc, Kflop or some of the more expensive options like Centroid Oak, etc.

At the moment I'm strongly leaning towards Linux CNC and mesa cards which I know is more than capable.! . . . The weak link here is ME.!. . I've never used Linux CNC or Mesa cards but I know a man who knows is onions, hey Clive S..Lol . . . I'm sure together we'll figure it out.!

Watch this space.!