Odd coincidence, I just bought today in a flea market a used RQ-L340 which is a similar but older model (my guess is early 90's) My experience with Panasonic stuff is that "it just works" and indeed in my case all it needed was a new belt (the old one was a bit too stretched) and two drops of oil in the motor bearing. I had a speaker failure once but it was a digital recorder; I stole the replacement from a donor microcassette recorder. Have you measured the impedence of the damaged speaker ?

Thank you so much sir! What a lovely job u've done. I am so happy it works now! Great video! Hats down. I wonder too, what was the actual reason of a damage, wherher that could be due impedence failure or something as @enricoself2256 wrote.