Do all of the above and let us know what you find. The true rpm was 1793. I thought was that I got the rpm wrong. More data will be provided if needed. You usually see 1x and 2x both.
First thing is, has the problem been there from the get go or is it new.
If this has always been there my first guess would be some type of structural resonance. Also a hint that it may be a resonance is the fact that it is vertical rather than horizontal. Chect the vibration again but on the casing as well as the bearings and if you can see if the whole machine is bouncing up and down or whether it might just be the bearing housing. If just the housing, it is probably resonant, but check to make sure that bolting has not come loose causing the resonance. If everything is moving together check to see if the foundation under the unit is'nt shaking.