[5Tractorguy]

My '61 5000 has a Midland Hydro-vac. Same symptoms with yours when I first got it. I used to have to pump the pedal twice to get good brakes, then a couple, then I took it for a drive one day and no amount of pumping would stop it.

Sent it to DS Parts Co. in Bluefield VA for a rebuild, now I can stomp on the pedal and leave dually skid marks on the road.

On those re-manned units.... make sure you call before you order! I have an uncommon Midland unit and Summit just so happened to show one on their site. After 3 weeks of not receiving it I called and apparently there was 0 in stock. They had to wait for a rebuildable core to come in (who knows when) to the Cardone Co. so it could be rebuilt and sent to me. DS had a 7-8day turnaround on the rebuild, ran about $260 with shipping.