Check that you have 10-12v on IC3 pin 8 and a high frequency square wave on pins 2 and 6.
If so, the bias trimmer might be off. Clip the scope probe to CP1 and adjust TR2. At some point
you should see a signal. Otherwise the chip is probably dead. Swap it with one of the others.
The balance trimmers TR3,TR5,TR8,TR10 should be centered but don't touch them yet.