I found a Fender bassman 100 (early 70's model)for sale and I'm pretty interested in it but there are two problems. #1 the tubes are blown (WHAT?! How do all tubes blow without serious problem?) #2 the person selling it stated that he ran it using only two of the four 6L6 power tubes. Is there a way that I can test the output transformer of this thing without any tubes in it?(the only salvageable tubes that I have are in my V4 right now) Also is it safe to run the Fender bassman 100 with two 6L6 if the impedance was checked?