I have a cheap Rikon 8" slow speed grinder and I'm having a hell of a time getting the (original) wheels to run true. They will put an edge on my tools, but the edge is far from perfect and there is considerable vibration from the grinder. I pulled the wheels off and measured runout on the arbor (measured as close to the threads ad possible) and it is about .0015". Is this enough to cause big vibrations? I've replaced the washers with machined washers and no matter how much fine-tuning I try to do, it runs out of true both axially and radially?

I have a CBN 180 grit wheel on it's way (a fantastic birthday gift), but I'm not sure how useful it will be if the grinder itself is the issue. Any insight would be greatly appreciated!