Help Altec Lansing 9444B

Hello, I need you!

I own 4 Altec amplifiers, 2 x 9440A and 2 x 9444B.
For the 2nd time my 9444B loses one of its power channels.
The first time, a technician replaced the 4 Motorola MJ 15025 transistors and the 4 MJ15024 transistors and it worked for a short time
Again the same problem, no left channel and the input fuse blown.
I have good knowledge of electricity, but not enough in electronics ...
I disconnect the current and signal inputs of the two channels, new 2A fuse,
and I reconnect.the problem arises when voltage is applied to the left channel.I unsolder the first 4 MJ15025 transistors and then I test, it does not jump any more,
but the clip lamp remains on ... and the resistor R30 5W 3K rises in temperature ...
I unsolder the last 4 remaining transistors MJ15024, The clip lamp goes out, the resistance heats up but at a normal temperature, like the right channel, between 30 and 40 °CI measure the input voltage to the 2 left and right pilot transistors NE5532AN 29,4vAre the transistors placed by the technician to replace the original Motorola's the cause?
do you have any idea to help me, and can you advise me of corresponding transistors.

Thanks for your help

Luciano from Belgium

Sorry for my bad Inglish