If it was working before and not now did you try replacing the check valve in the face of the booster?

Like Blusmbl did,, I have a pump and reservoir.

I have an inline check valve before the pump T's into the brake booster line. All the pump does is draw a vacuum for the booster and the check valve keeps it from leeching down.

I got rid of my noisy diaphragm vaccum pump and got a vane pump from a Volvo turbo car out of the junkyard.

There are a lot of turbo & hybrid cars in the junkyards and many have electric vacuum pumps. They are quieter and cheaper than the old diaphragm pumps.

You may have to wait for it to vacuum down before you drive. I added a vacuum switch to my pump circuit to cut it off when it isn't needed.

Hope it helps.