Is the PSU or the frame holding the filter vibrating as much as the filter? Or is the filter just vibrating so severely because of a resonance? If it's a resonance, you can just tape/glue some weight to the filter to change its resonance frequency. It doesn't take much.
Way back when the DC-10 and L-1011 were being designed, because the third engine on both planes was mounted in the tail, both manufacturers ran into the same design problem. Small vibrations in the engine and the flexibility of the tail sets up a resonance, causing a pounding noise and sensation. The Douglas Aircraft engineers took the brute force approach and lined the entire ceiling of the passenger compartment beneath the tail with lead to reduce the noise. If you've ever ridden in the rear of a DC-10 (or MD-11), you can still feel the vibration at certain engine RPMs. (The noise sounds like when you stuck a baseball card in the spokes of your bike wheel as a kid.)
Lockheed's engineers went through the trouble to figure out exactly what was resonating, and changed its spring/mass/damper characteristics to eliminate the resonance.
https://en.wikipedia.org/wiki/Resonance
The Douglas approach is what you're taking by trying to tape the filter in place or wedge something in there so it can't vibrate. They won't really help since even a small residual vibration at the same frequency will eventually lead to the filter vibrating almost as strongly, because that's what resonance does. You have to change either the frequency of the vibration, or the frequency the filter wants to vibrate at.