Please excuse me if I am posting off topic,
I find that many people of the Drafting Community are using The Hewlett Packard series plotters for extremely valuable output to there operation. In many areas across the Nation, service is hard to find or very expensive.
90% of the failures on the 220, 330, 350c, 430, 450c, 600, 650c, 700, 750c, 755cm plotters are caused by the main carriage drive belt. I have compiled a kit containing a new belt ( 24" or 36" ) step by step instruction, a URL to the complete service manual and Phone support if you really screw it up ..
go to http://lorand.net for information