Just in case I'd try re-bleeding the system again. A little bubble of air can be in the system which is compressible enough not to pressure up the cambers to stop the pump. Both front and rear, I'd recommend to bleed them from the modulators first, then from the brake calipers in the usual way, run a good 250-0,5L of brake oil through the system (you can re-use it if it's a new oil - keep pouring the same fresh oil back into the system - your mission is just to get all the air out). Don't forget to reset the ABS after the procedure too.
If all else fails then your options are getting another s/h unit or just strip it off I reckon...
Good luck,
Margus
Took it for a 100 mile trip in the week and everything is 'hunky-dory'. I also bled the pump after overhauling the unit, so yes, it could have been air bubbles as you suggested.
