need help with power master

[7007v6buickman]

my power master is making a click/thudding sound.Some time brakes get real hard to push down, WHEN THIS HAPPENS THE BRAKE LIGHT FLASHES

 

[SSL86GN]

Mine has been doing that too. If the pump side had air in the system, it seems like it might make such sounds and it also seems to go away after a few cycles - maybe because the air gets worked out?
I am thinking about just rebuilding the master cylinder and replacing the accumulator.

 

[gsgnnut]

Do yourself a favor and swap it out for vacuum or hb. You will not regret it. You will spend waaay more trying to fix a pm and you will be risking your life or wrecking your car or worse. You can always swap back if technology ever makes pm s more reliable.