A few things I have observed over the years you might want to check.
Take a flashlight or something and look at the actual contacts in the port and see if they are bent. Sometimes the old cheap 4 in one carts have poorly made PCBs what arent beveled correctly or are too thick and squish the pins and they no longer make good contact. It looks like an official one in the pic but unless you have had this since new who knows what someone threw in here. see here for some more info on that
Also these backup carts do just sometimes go bad though I don't know if I have ever seen an official one go bad but buying a new one to test may help with that as they aren't that expensive. They also usually have lots of built in features like an action replay and acting as an extended ram cart. Just make sure to try and check that the pcb is made correctly with that link above
Like separately? I've put alcohol on the contacts of the card and then inserted and removed into the system , over and over, to get the oxidization off. I have to do that with my n64 from time to time.
New OS what do you mean? My SS has a fenrir and a working memory card slot and I still find it a pita dealing with saves on this console. Luckily batsugun doesn't really need all that much save wise.
That's fair enough. I had no nostalgia for it and came across one cheap console with a broken power supply. Swapped that out then upgraded it. The price of games for the system are pretty crazy especially for Shmups.
I do quite enjoy it though I had a play station growing up and if I had the choice again it would be the PS. Though the Sega saturn is a neat machine and it does have some interesting games.