[morzh]

Here are my thoughts on dim bulb tester.
Let me just say it out loud: it is not a tester. And my view of it is dim

I grew up learning to use all kinds of things. We in my old country had no access to good instruments and had to resort to all kinds of things and get crafty. But that was a necessity. Not a choice.

If someone wants to use a "poor man's tester" phrase her - OK, I could agree with this.
But a Variac is not expensive and beats the crap out of light bulb "tester" any time of the day.

I never once had to use it. Hopefully never will. It is inconvenient, uninformative and ill-suited for good troubleshooting.
Also many use it on sets before having done recap which I disapprove of anyway.

I am not advocating spending big bucks - I do know that we have a lot of folks here who are not exactly rich.
But instrument does not have to be expensive, it could be cheap, for all I care - it just has to be a right tool for the job.

A Variac and a multimeter is all I EVER use to fix any radio. And a multimeter gives you TONs of information, if you know how to use it.
A dim bulb tester gives you..well....glow. Even if it is indicative of something, this by its usability loses to a $5 cheapest Chinese meter.

There are many traditions in most any hobby that, if examined, prove to be of little effectiveness. People still do it, some out of fondness to "good old crude methods" (remember when I could make a meal out of old wallpaper? And lived to tell about it?), some just because they were told so by older more experienced folks and simply do no know better.

Use the right tools. This will cut your wasted time about 90%. You need but a few. Dim lightbulb tester ain't one of'em.