For horizontal cleaning AIVS remains my choice:
http://www.theaudiobeat.com/equipment/aivs_products.htm
For ultrasonic cleaning I use:
200ml Isopropyl Alcohol, 5ml Ifotol wetting agent - that's for a gallon of distilled water. I'm thinking of adding a bit of Hepastat 256 to that mix.
https://thevinylpress.com/timas-diy-rcm/