I've been through 4 or 5 card readers over the years, so yes they do die. And yes, the might run in "maybe" mode for a while.
I believe the issue is with the pins and connectors. On Compact Flash cards the pins and slots are very very small. Female slots can become contaminated with dust or dirt. Repeatedly inserting a card might clear out that debris. Male pins can become bent or coroded, and are impossible to clean.
Then, of course, there is the USB cable. Two more male/female connections to fail.
Always need to do a "binary chop" to isolate the problem. Swap cards, swap USB cables, swap ports, swap readers, until you find the combination that fails in all cases.