The problem you mention can be caused by a multitude of different things, however a simple test that you can carry is "IF" your set has a headphone out socket, push the headphone jack rapidly in and out a few times just in case the internal contacts have got oxidized, likewise if it has external speaker on / off switch, move that in a similar fashion to the headphone plug. Should your set have these facilities and after carrying out the aforementioned procedure it did not help the situation then it really requires a bench service to investigate the reason for the problem. (PS: A long shot! but also try another set of batteries in the remote control)