Abstract: A copying machine in which a photo-receptor sheet, wound between supply and take-up reels, serves as an intermediate web which is charged, exposed and developed with toner; the toner then being transferred to copy paper. The photo-receptor sheet is advanced incrementally from the supply reel to the take-up reel during each copy cycle. After substantially all of the sheet is wound on the take-up reel, it is rewound on the supply reel, following which it is moved once again in incremental steps in the forward direction during copy cycles. The supply and take-up reels are mounted in a highly compact module which is easily plugged into or removed from the base section, without requiring any threading of the photo-receptor sheet over elements within the base section. In this way, practically all that is required during a service call to replace the photo-receptor sheet is to substitute one module with a new photo-receptor sheet for the previously used module with the old photo-receptor sheet.