Vintage Simpson Tube tester Model 330 in wooden case, this came from an estate sale from a former Montgomery Ward employee, I dont know how to test, I plugged into my outlet and moved a couple bottoms an the meter needle moves; I have taken photos with the needle in different locations. I think there is a loose part or screw because when i turn the box over it moves around the case. I am selling this as it is, one similar sold untested for more, Please ask any questions you may have... or if you want more photos or info I can try to answer all your questions thank you for looking!