Need Mono Blend - Will This Work?

Yes, this will give you a mono signal, but usually when this is done to set azimuth, one channel is hooked up out of phase. The idea would be to adjust the azimuth with a mono signal so that no sound comes out of the speaker(s), the anti-phase channel exactly cancelling the in-phase channel. I would caution you that this method of setting azimuth is loseing currency, because if the generator does not produce equal voltage you will be fudgeing the azimuth to compensate and you will end up with the stylus not being tangent to the groove. A bad situation for both stylus and record wear. The old method, of putting a small, flat mirror on the platter mat and trying to get the body of the cartridge parallel, may be preferable, but has its own issues.

Thanks, that makes sense about the signal. I'm using a test record that says it has the two channels out of phase. I'll go back and make sure that's correct.

You can also use any record with stereo test tone band, Reverse cardridge leads on one channel, Y it out; and use headphones, makes the job a little easier.