Up for sale is a Heathkit Model TC-2 Portable Electric Vacuum Tube Checker. This appears to be a working unit (although I am not an electrician).I plugged in a Z525 bulb (not included) that I have from an old radio, set the dials/knobs according to the chart, and the meter showed in the GOOD range (see photos).The case has a few rough spots (see photos) and the grid clip outer wire casing has some cracks (see photos). The online manual for this unit can be found at: http://www....grandpas-shack.com/parts/datasheets/TC-2(Heathkit-1955).pdf Email with any questions.Free Shipping!