Weird Prices on E-Bay

Hi All Reminded of this, I did a search for Moseley and found an articlethat said that Moseley was bought out by HP. It seems that HPXY plotters got their start with Moseley.The plot thickens ( pun intended ).The search also brought up one of the ebay searches for plotters.There was an early add for a Moseley plotter but also a number ofother XY plotters as well as manuals.Looking to see what was there, I came on a buy it now fora HP 135/135A plotter maintanence manual. I blow up the pictureand what do you think. The knob pannel looked just like my plotter.A closer look even had the Moseley lable on it.I went ahead and bought it of course.I'd been trying to fix the one I had but it looked like the outputtransistors had been failing ( older germanium types ).I'd tried to trace the wiring but it is difficult without cutting thewire ties, that I didn't want to do.With the manual, I'll no longer need to do this.It is interesting, how it works though. Instead of a DC servo motor,it uses an AC synchro motor. It chops the error signal and uses thatto drive the motor. A clever way to avoid DC offset with the earlytransistors.I did get a kick out of one of the ebay adds. The wanted about $200for a plotter and said it was in excellent condition. In the picture,one could clearly see two of the switch toggles broken off. Oops!Dwight