The gyroscopes are spinning, but not fast enough. And/or, the erecting system in each instrument cannot operate because of low air flow.
Easy thing first, replace the vacuum system filter, and check the air supply side of the system for obstructions. If the air source is obstructed/limited, the vacuum pump will pull, and the indicator indicate an adequate vacuum, but the flow of air at that pressure (vacuum) may not be adequate to run the two gyros.
Next thing, is the whole vacuum system in conformity with the original design? Sometimes components are swapped. they seem to work, but really don't work with each other. If you're running a working vacuum pump, varied gyro instruments should work with it. But, if you've a venturi tube, it will not run the newer smaller gyros properly, a venturi will only run the older, larger "AN" style gyro instruments. Sometimes the older instruments are replaced for new (which is a good idea) but the venturi tube is not replaced with a vacuum pump and system. The whole system must be in harmony.
As both gyros seem to have erecting problems, it's probably not the erecting mechanism in both the instruments. Were it to be only one instrument acting "drunk" and not erecting, and there is no other reason, it should go to the shop, it's erecting air passages/blades are sticking or blocked, and should be corrected. Otherwise, there's not much else to check for, vacuum pumps themselves either work or they don't, and the suction gauge is telling you that!