Strange amplifier problem

Dear mates,
I started to experience a strange problem with my amplifier. Here is the description.

1. I'm listening to the music, everything is OK. Then I make a break for about on hour or two. Want to listen again, but there is no sound, though all tubes are glowing.

2. I check the CD player (change tracks, switch off and on, etc.), it is OK.

3. After some time I see a spark near the IEC inlet and check the fuse - it is blown.

This problem occurs for the second time during the last week. It is obvious that something inside the amp makes the fuse blow.

Some time ago I noticed another problem - when the amp is running, the left output transformer runs warmer than the right one. I wrote the dealer and the manufacturer, but company's president answered that this was normal because the left transformer is closer to the tubes (!!!), though this is not the case - they are symmetrical. The company's president either does not know what his company makes or deliberately ignors my problem in order to rule out any attempts to bring the amp back to him.

My numerous questions about the transformers and fuse remain unanswered.

Before bringing the amp to the dealer, I will appreciate any opinions of those who encountered similar problem and to whom such symptoms are familiar.