Here is how to clean seriously dirty records. This is better than any ultrasonic cleaning machine according to all who have tried it. For routine cleaning I have used a VPI HW-17 for years, but recently started using Tergitol in accordance with the instructions in this same paper and it definitely works better than other cleaning formulas I have tried in the VPI.
Vinyl Record Manual Cleaning Process - PAC-Vinyl-Records_2020-05-19.pdf
Vinyl Record Manual Cleaning Process - PAC-Vinyl-Records_2020-05-19.pdf