Hi I'm a new member and I need some assistance with my Pioneer SX-828 stereo receiver. I want to clean out the pots but I don't know what size the set screw is that holds the tuner knob to the shaft. The service manual says use the provided L shaped hexagonal wrench provided. I bought the receiver used from a local record store and the wrench was not with it. Does anyone know what size this allen wrench is? Any help would be greatly appreciated. Thank you.