getting pump out of mid 80's Murex water cooler?

[graffian]

It's a transtig200 squarewave with what looks like a tall plastic fuel cell on the back of the welder and the
pump seems to be pushed in a rubber collar?

The pump has always been very noisy.
The pump has been a bit cranky for a few years, every now and again you have to grab the pump wiring and
hose and give it a good shaking to get the pump working! Anyone any idea how I remove the pump without breaking anything. It seems to be pushed in but I have given it some stick a few times and it didn't want to come out.

 

[graffian]

My abusing the hose to get the thing working had broken the pump. but the
pump was so sized I dragged the armature out of the body of the
thing getting the piston out. I can't get the rest of the pump out easily without
doing more damage. Anyone heard of Guinard pumps?

Here's the old pump, the black plastic bit on the right broke, it's supeglued in the pic and
I made a replacement from aluminium. I think it's going to leak, One of the seals runs
on the piston, where I was holding it with pliers to pull it apart. Think I may need a replacement.