to buy or not to buy (ultrasonic record cleaner)

For those that already have extensive experience with an ultrasonic, is there any prep you do prior to use?  Visual inspection for any blemishes or material that probably should be removed with a fingernail or something?

I bought some used ones the other day and ran them through my (admittedly low-end) ultrasonic and they are pretty clean and shiny now, but, I found the cleaner won't get rid of things like the chunk of chewing gum (small, almost not noticeable) that some prior owner left deposited on the vinyl. 

Of course they also don't seem to be able to clean up 100% (although considerably) the results of many many abusive plays over the years by owners who had probably played them on groove-grinder turntables with dust all over the stylus and/or coin taped on the cartridge head to keep the needle in the groove.  The LPs quiet up considerably after a clean in the ultrasonic but can never be made perfect again if they have been damaged, at least in my opinion. 

I preclean any used album and some new ones. Ultrasonic is good at the fine cleaning but the basic stuff I do manually via a Monks Omni. At the same time, I inspect the record-- Neil got me onto using a UV light which is instructive, but not all telling. What you can see is some particulate and differences that aren’t as visible in normal light in the vinyl itself- not that there is anything you can do about the latter.
Given how the Monks works, if a record has a warp, you will know it. In those cases, after a preclean, the record will go into an Orb made DF-2. Final cleaning via US (currently using the KL which is hanging in there). I rinse, using high grade water, a vac dry on the Monks. My set up is shown in my system photos on Audiogon, but I’ll include a shot here: https://thevinylpress.com/app/uploads/2017/12/DSCF0766.jpg

@whart2 thank you for the reply.  Very nice cleaning setup, I need to do some basement remodeling to accommodate something like this.  For now my US lives on a borrowed table whilst I do work on either side.  Gotta pay the bills of course.  I certainly will plan to do some better visual and preclean before my next batch of US.  Great tips, thank you.  The Monk machine is very interesting, I had not seen nor heard of one of those before.

’Twas the original "automatic" record cleaning machine borne out of Percy Wilson’s papers on vinyl record contamination. There was a test mule, photograph of same floating around on the web somewhere, and Monks was the one to commercialize it. I saw my first one circa early '70s at the high end salon in Pittsburgh, run by the debonaire Tasso Spanos (lovely guy with ears and a real sense of the high end back the day). Tasso was one of the few I knew who had one-- they were really aimed at libraries, radio stations, and in the UK, facilities that would offer record cleaning as a service.
Tasso’s old machine showed up on E-Bay or Audiogon several years ago as a rusted out hulk.
When Monks the Elder died, the company became dormant, though there were still folks out there servicing them. Monks the Younger rebooted the company a decade or more ago, and this is one of the newer models-- finish may be a little nicer than the early ones, but the unit is in many respect the same British engineering- quirky, but it gets the job done and I like it as an artifact. (The pump actuator is from a Mini with a windshield wiper icon-- I don’t use the fluid brush head dispenser because I use various fluids and a pure water rinse). The machine is still made as far as I know, although Monks recently introduced a line that doesn’t rely on the thread buffer that was part of the design of these-- I have not seen or played with these newer ones, which I gather are priced at a few grand as opposed to several few grands. It’s a keeper.

Yes the Monks RCM are back and now a threadless design that cost $1000. The original Monks machines are still being made but have been converted using the same threadless design as well, from what I've been told. Easy to use and very quiet.