Definitely not normal, I installed a shaker in my Star Trek Prem, should be exactly the same, and I have no buzzing at all.

I would try it without the plastic shield in place. It's just there in case something flies off, but you should be fine to leave it off for brief testing. Will at least tell you if that's the source of the noise or not.

Make sure you have beer seal on the lockdown bar.

First thing to check is the long screw that goes parallel to and above the shaker motor. This may need to be tightened, but only tighten it to the point that the vibe noise goes away. This secures the motor firmly in the bracket.

Isn't some cables touching the shaker ?

I believe this is only on the PBL Shaker Motor Setup.. But this might be a PBL shaker setup. Thats the only time I have seen this issue.

I believe the shaker I installed in my ST Pro is also louder than it should be. It is rather loud itself, and also causes more audible resonances in the cabinet and backbox than I imagine it should.

Unfortunately, I'm out of luck with the two suggested adjustments I've found, as mine doesn't have a screw across the top of the bracket, and the manufacturer put Loctite on the weight's set screws (so I can't easily rebalance them without breaking that down, which I'd rather not).

I don't have a good reference point though, as the bars where I play other tables tend to be really loud. Would a kind pinsider out there with a good motor be willing to post a quick video of the shaker coil test with the glass on? I looked around, and couldn't find anything quite like that.

You shouldn't be hearing your shaker at all with the glass on. Feel it, not hear it.

Thanks for confirming, Aurich. That's what I suspected, unfortunately.

Tighten the threaded long bolt that goes through the shaker housing. Just go into shaker test and tighten it until the noise goes away. 100% the problem.

Mine doesn't have the threaded bolt, nor is it drilled for one, so that's not an option in my case.

Why not break the seal and try to re-balance. Succeed or fail you can always put a drop of loctite back on... if you really need to.