Brake Booster Issue?

[Glenn 'Stinky' Stankevicius]

After any tips before I start pulling stuff apart.

Back Story - My FE Sedan has LH/X Torana front discs and HR rear drums, LC Torana booster, master cylinder and brake block switch.

Sometime after it's last hibernation the Brake warning light came on and has stayed on since, brakes seemed hard to apply but were safe enough for driving.
Up on stands the other week we found the rear brakes didn't work at all, seized rear cylinders that we replaced. Bled the whole system, brakes are still hard, when first built you could lock up the brakes if you got on them hard enough, not now.
Pulled the vacuum line on the booster, plenty of vacuum. Pulled the PCV off the booster, we could hear it sucking air in once the PCV was removed so it is air tight.
I suspect the booster is shot, could it be anything else?

[Harv]

If you are sitting in neutral at idle, and put your foot on the brake, does the idle speed change? If so, it could be a split diaphragm.

I spent a long time chasing a split diaphragm in the EK wagon. Same drama - hard pedal. Dumbass me didn't troubleshoot it properly... booster had been reco'd, but a long time ago.

Cheers,
Harv

[hsv-001]

I have run a 1981 Datsun Bluebird booster for 30 years on my FC Van with HR brakes rear and front . Just an option if you can find one .