I have a qtron+ that has very low output for some reason all of a sudden...
 
Is it worth getting this fixed??

That happened to mine. I took it to get fixed and they gave it back to me saying nothing was wrong with it. I then stopped trying.

Glocke..I have one of these and it did the same plus it made some weird noises too. I changed the battery(unless it has external PS) and I cleaned the jack socket contacts using some fine grade  sand paper. Had no bother since.