1990 ZR-1 secondary actuators binding?

[Ccmano]

Have you tested the vacuum check valve? I have see at least two instances where the check valve failed causing the pump to run continuously subsequently burning out the pump. Replacing the check valve and pump restored the secondary system. I now always replace the check valve when going under the plenum for the first time. It’s cheap insurance on a cheap part that’s prone to failure.
H