Agree with Jeffrey.
As many know, I also purchased brand new replacement lamp grids for my VCL4500. I then step-wedge calibrated mine to one-half contrast grade levels using Ilford MGIV FB & RC, then interpolated to one-quarter grade levels. I also created a matching set of exposure compensation factors for each fractional contrast level. This allows reasonably accurate jumping around between grades without needing to start from scratch with test strips for each change. Only took a couple of days to do all of this.
Now I can now simply select the initial contrast I want in quarter-grade increments, set the dial and go, confident it's ANSI-correct. Or when changing contrasts simply use the exposure correction factor, multiply or divide, and go.
These are really cool heads. And that is a great price, especially if it's a low mileage unit.
Ken