The 19 pin port is for an external floppy drive. You know, I'm not sure Apple ever made an external 1.4 MB floppy drive for that port - I can't find a model number for one. An external 800K floppy would work: though you'd be limited to smaller capacity disks. Those are model numbers M031 or A9M0106. But in my (very biased) opinion, instead of a standard external floppy drive, you'd be better off with a floppy drive emulator that loads disk images from an SD card - I sell a tool called Floppy Emu that does this: www.bigmessowires.com/macintosh-floppy-emu/ Then you can have hundreds of Macintosh disk images on a single SD card. Sorry if I sound like a salesman.

Your fastest and cheapest solution is still going to be servicing the existing drive yourself. It only needs a long handled Torx screwdriver to open the case, and then 30 minutes of your time and some grease to clean and lubricate the drive mechanism. You could check to see if there's an old internal HD in there at the same time, upgrade the RAM, etc.