I have properly cleaned 11 MVS quite recently. I'm fairly new to MVS gaming and started picking up carts in 2014 so still very much a noob. I always clean retro video games as best as I can, I would carefully remove the PCBs only opening the shell a small amount and used to use IPA/rubbing alcohol on the contacts and then would clean the shell. However as I have come to realise IPA might be ok for home console carts that are stored in cases (mega drive etc) but not for the more exposed MVS arcade carts. I was getting lots of random resets a couple of months ago on my Omega CMVS and was wondering if it was dirty contacts, basically I opened all my games again and did the following:
Removed all PCBs, washed them with soapy water and used a toothbrush in the sink, rinsed with distilled water and all the dust and grime is now off with very clean boards. For the contacts I used a red eraser, IPA and finally DeOxit D5. I can't stress how important a good electrical contract cleaner is, I was sceptical at first but many rave about it on here for good reason. My q-tips came up black when using it on what I previously thought were "clean" games. - Buy this stuff and clean your carts and slots properly, I have since had no issues with games resetting with many hours of testing. It might be expensive but you will be surprised just how dirty your games are, I now use it on everything I pickup SNES, MD, MVS its doesn't matter.