ACK! Dishwasher?
No fluids, please, without subsequent rinsing and drying. I don't believe for a second that a Discwasher record brush does any cleaning at all, just losing wet dirt around.
Use a carbon fibre brush for pre-playing dusting.
Look baldrick, I'm just trying to offer some constructive suggestions. The fact that the OP has a myriad of gizmos for his turntable, yet didn't know he should be cleaning his LP before every play shows that he does need some education. Just as he asked for.
If he could actually "see" gunk being brought up from the grooves by increasing his tracking force this shows that the record is massively dirty. Incredibly dirty.
The fact that it only happens with one LP in one spot shows the problem has nothing to do with his system, and everything to do with the LP itself. Hence, my suggestion of cleaning.
Your suggestion of using a "carbon fibre brush" doesn't help much without a recommendation of a brand and how to use it.
Poor quality carbon fiber brushes can scratch the LP (carbon fiber is much harder than vinyl). Also, using a carbon fiber brush without an adequate electrical connection to ground can create a huge static charge on the record. Attracting more dust, and possibly even a static discharge that can damage his cartridge (think of about 10,000 volts in a cartridge that is designed to output 3.5mV).
Regarding the Discwasher...first, better than nothing.
If we assume that today's Discwasher is the same product from the 1970's-80's (I have no idea if it is), then I can assure you it's been tested and analyzed many times over by all the old mags (High Fidelity, Stereo Review, Audio, Stereophile, Absolute Sound, etc.) and has been found to work well. There are better ways I'm sure. Again, I have no idea if today's Discwasher is the same construction as from 40 yrs ago, but it's better than doing nothing. Use the Discwasher with whatever fluid you think is best.