I was successful in finding not only a 4052 with 4662 multipen plotter and 4631 hard copy unit (lots of internet searching) - but also a 4054 on EBAY! I got the 4052 working after repairing the tape drive board and cleaning the tape heads. The 4631 needed new paper and one of the toothed belts - got both and it works fine. The 4054 repair consisted of replacing one of the 16k bit DRAMs! I have also added two Tektronix 4041 GPIB controllers with one line LED displays and built in thermal printers. I now have quite a collection of 4050 and 4041 series tapes - some with my old programs from the late 70's in the USAF, some including the Tek System Tapes and some game tapes, also some of the 4052 cartridges. Sorry, at this point I'm interested in keeping my collection. Contact me direct if you are interested in any tapes, though. Monty McGraw Spring, TX (near Houston)