I too had the similar problem with keys with stabilizers. In my case, the keys themself felt smooth to touch but stabilizers were making rattling noise. My HHKB had lube on the stabilizers, but my RF silent version lacked lube on the stabilizers except for those on space bar. As a result, there was rattling sound if you hit backspace or enter.
Also, I had couple of scratchy keys to touch. The scratchiness was coming from the springs and couple drops of lube through the hole on PCB solved the problem. (I used Krytox GPL100 for this purpose. The lube is not cheap, but it is safe to plastics and rubber. To my knowledge it it the most chemically inert lubricant and shows top of line performance.) Before trying lube, I tried to reposition the springs, but it didn't help. But it was certainly springs because without the springs the scratchy feel was not there. There may be different solutions, but I am just sharing how I solved the problem.
I am not sure if you have the same problems, but the above are what I experienced in Realforce 87U silent version. I addressed all of the problems, and I am pretty happy with my RF.
