I recently obtained an Okidata ML-182 impact printer in very good physical condition. It hadn't been used in a while, and the carriage movement motor was rather stiff. I was able to free it up easily and now the print head seems to slide back and forth without issue. This printer is a unique design in that the print head is not driven by a belt--the stepper motor is right on the bottom of the print head. It runs along a toothed plastic track.
The problem has to do with this motor. With a ribbon loaded, the motor has trouble moving the print head back and forth. More often than not, it will stop running with the ALARM light turned on. Strangely enough, the carriage motor will run *fine* with the ribbon removed. (I haven't run it much like this for fear that the print head might seize up without a ribbon going along past it, as the ribbon might lubricate the pins in the print head.) I've tried several ribbons and none of them make a difference. Two of them are brand new, the third came with the printer.
In years past, I had another example of the same printer. While it ran fine, the carriage movement motor was sluggish on that printer as well. I'm hoping that someone else has seen this and might know of a fix.