studiomaster p series 4.5 amplifier lim led on problem

Hallo there,

I have a studiomaster p series 4.5  amplifier and have used for a couples of year withoutb any problem.
But now the right channel become hot in normal uses and after a couples of uses  the lim led i on and there is no output coming from the amp.
What is the cause and how will i retify this problem?

Thanking you in advance!