I have a Teac Receiver AG-D9100, sound cuts off, but if I touch the master volume knob it comes on for a short time. What to do? jmf

Check mute is in off position. If problem persists, the check plus minus 5V supply section and measure voltages at IC30.
Here is service manual for help.

TEAC AG-D9100 D9200 SM Service Manual download, schematics, eeprom, repair info for electronics experts (elektrotanya.com)

Here is user manual for help
Troubleshooting - Teac AG-D9100 Manual Del Usuario [P?gina 26] ' ManualsLib

Take it to a repair shop.

I'd connect it between the "Tape 2 Monitor" jacks. On the TEAC, the "Record" jacks are audio OUT and the "Play" jacks are audio IN.

Connect the Record to the EQ's IN and the Play to the EQ's OUT.

Select your source (AM, FM, Phono, CD, etc. and when you select Tape 2 Mon, you'll pass the signal to the EQ to shape the sound of the source. With it unselected, you'll bypass the EQ.

Check your speaker and speaker connections. Do you have normal display? If so, after checking your speaker and speaker connections and they are ok, you might have a problem with one of your output elements (Mosfet).

short on the board

Possible that there is fault in the preamp analogue/logic control. When you touch the volume control knob the static from you partially injects the circuit to work and thereby conduct to produce the volume.
The volume controller is an analogue rheostat coupled to a circuit that can be the suspect , it can even be a fault- open circuit- of the controller.
You can remove the top cover after disconnecting the power supply and check behind the volume knob for the circuit. If you are able to test this circuit , it will confirm the case.

You have to enable them and turn the volume on them up separately with the speaker config, level trim, and up/down select buttons on the remote. You can also adjust the rear speaker delay time or just hit the test tone button and adjust the volume on each speaker separately as it goes through them one at a time...

Yes, and if you have a cable/sat/dvr box why don't you just run ITs best TV-related audio into the receiver without watering it down through your TV?

I'm not so sure that running the TV video through anything else serves any purpose. Once TV has it where else do you need it?

Always be that legend when the audio amplifier IC damaged

you can download a manual for $9.99 from User-Manuals.com....I did this today and the manual is identical to the original it seems