Shugart Model 801 (8 inch floppy)

I have the above drive. It was shipped to me bolted in an enclosure. During shipping, it was badly shocked, shearing off the mounting bolts and damaging a couple of components on the electronics board. A couple of resistors and caps had their leads cut. Some creative soldering fixed that. One diode was smashed. It was on of those little clear (glass?) diodes. Are those called zeeners or something that starts with "z"? Anyway, I didn't have a replacement, so I just removed the leads and left it at that. Later I decided to go ahead and try the drive, and it worked. If somebody has the schematics, the silkscreen next to where the diode was is "C1" (it is in one corner of the board). Are there often nonessential components in older hardware? Is it actually nonessential or is some signal being compromised or some other component being overstressed? Bill Sudbrink