Struggling to keep knife flat on the stone

[BPalv]

I have encountered a similar issue about keeping the blade flat on the stone. The blade holder keeps hitting the post of the threaded part of the universal support bar. I am unable to slide the blade holder smoothly along the bar. What should I do to avoid this?

I believe I have been experiencing the same issue (occasionally) as you.  I believe the root cause is the KJ-45 jig.  Is that what you're using?
The collar on that style jig is a tad more than 90° to the USB.  It is flared out a bit causing that.
Someone had a similar issue and just filed off the area it was bumping on the USB support bar.  I will be doing mine in the morning.

[RickKrung]

I have encountered a similar issue about keeping the blade flat on the stone. The blade holder keeps hitting the post of the threaded part of the universal support bar. I am unable to slide the blade holder smoothly along the bar. What should I do to avoid this?

What is the configuration you are using?  Vertical/rear USB (edge-leading) or Horizonatal/front USB (edge-trailing), with or without an FVB?  Only happening when grinding or when honing on one of the Tormek honing wheels?  Photos showing when it is happening might help alot in understanding how/why this is happening.