Electron Tubes

Dear Friends,

I have an old ATS 100 Twenty amp. Lately the pre-amp circuit has been giving problems. I opened up the amp to replace the two electron tubes but unfortunately the tubes part numbers have faded and could not be seen. I would be very thankful if someone could let me know the tube part numbers. It would be more helpful if someone could send a copy of the schematic diagram for this amplifier.

Thank you in anticipation

Carlos Rajoo