Las Wedrowiec

For reference, is there a way to do that without an external amplifier?

My apologies if this is in the wrong forum. Years ago I came under the possession of a beat up pair of Realistic Nova Pro headphones at a garage sale for two dollars. Not in the best condition, but serviceable enough for use. For a while now in the absence of speakers and disposable funding, they've served not only as my main choice for computer audio but also the headphones I carry with me to provide personal audio on the go. In the past two months alone, I have opened them up multiple times to replace oxidized connections, resoldering almost every connection in the left can alone, to maintain their functionality. Yeah, even though they're collector's items of sorts, I could just buy another pair in excellent condition and replace this one outright, but my insanity leads me to find pride in maintaining what I have instead of outright replacing it. Plus, it's a hobby between my studies. For the past two weeks, I've had to tug at the wire that bridges the two cans together where it enters the right can for the right speaker to work properly. Sadly, I put them on earlier this evening and found that the right speaker is now completely dead. I've made lacerations in the wire in multiple places, completely removing the core wires from the wire encasing on the right side to check any breaks in the wires, to which I've found none. I've been using a multimeter's resistance function to attempt this, and to no avail can I find anything wrong myself yet. How do I go more effectively at checking the connections? Perhaps I'm looking in the complete wrong place for a bad connection? Is it proper to check connections by checking for a change in resistance? Or, in the event it's the fault of the variable resistor which regulates volume control for the right can, how may I easily check its function without sound in the speaker? The circuit for these is pretty simple, considering they ran from 1970 to the mid 80s, but I may provide pictures of the wiring if needed.