O.k, let's go back to square one.....Was the focus any good prior to the resistor mod? Or, were you attempting to "fix" it by doing the mod in the first place? Since you have SD187 tubes you should NOT have an additional resistor connected to the flat focus resistor (only needed for the MS107 tubes). From reading your previous posts it seems that you backed out of the mod by replacing the bias module with another one, correct? This one has the factory focus resistor, right? Now, with the focus set to '5' on the remote (don't touch it again) put up a test # pattern and turn off the red and blue tubes on the bias module by sliding the appropriate slider switch on the top (near the focus pots). You should just have a green test pattern showing......Now, turn the green focus pot counter clockwise all the way and then start turning it clockwise slowly......Does the thickness of the lines in the test pattern start to collapse and then expand again the more you turn it?
Have you done any of the stigmatism and flare adjustments yet? It's possible that the flare adjustments are way out if the line does collapse and at least start to expand again......There are quite a few posts already about setting "stig and flare" so have a search around and if you still have questions let us know.....