Rear brake compensator leaking

[Ben]

Hi all, 

I've got a leak from the rear compensator. Even 
before it was leaking I'm not sure it had been working correctly as my mot tester said there was little effort from the rears.
Looking at it with the car in the air the piston was in/closed, and looking at which way the trailing arm would push the spring and rod it looks to me as if it would try to close it further, which can't be right?

I'm considering getting a new one off eBay for £115, and trying to get it set up well. Also considering removing it along with the abs and replacing with a bias valve in the car. Or possibly two bias valves to retain the abs. It's a road legal track car, only driven on the road if it's dry or to get it to a track. 

Any advice welcome please and thankyou.