I am at the end of my rope, please help

Thank you all for the advice. This all happens before the phono stage so we can eliminate that as a problem. I think, based on how confusing this is, I may be having two problems at the same time. One looks like it may be a cartridge problem. When I use my meter to check the tonearm wires, the positive goes to positive and negative goes to negative BUT when I hook up the cart each wire goes to both positive and negative of the RCA plug. In other words, red lead goes to both positive and negative on the RCA plug and the green lead goes to both positive and negative on the RCA. The same thing happens on the other side. When I remove the cart and touch my meter to the the red and green pins I get a complete circuit. When I touch the white and blue pins on the cart I get a complete circuit. I don't think that should be happening. when I do the same to my backup MM cart I do not get a complete circuit. I am thinking that the cart has a short. Seems a little strange that it would be on both sides but my question is, Before I spend thousands on a new cart, is there any difference between a MM cart and a MC cart that would cause a complete circuit on an MC and not on an MM? Am I supposed to get a complete circuit?

I never enjoy being the bearer of bad news, but I would absolutely not put an ohmmeter across a phono cartridge, or across a cable that is connected to a phono cartridge, especially a low output moving coil. The meter measures resistance by measuring how much current flows through whatever it is connected to, in response to a voltage it applies through its own internal resistance. That current will be very small in relation to the current-carrying capabilities of most devices or circuits that might be measured, but I see no grounds for confidence that it won't be large enough to cause damage to a lomc.

Is there any difference between a MM cart and a MC cart that would cause a complete circuit on an MC and not on an MM?

Since there are far fewer turns in the coils of a lomc compared to a mm, the resistance will be much less in a lomc. As a very rough ballpark guess, perhaps a few ohms in the case of the lomc, and many hundreds of ohms or more in the case of a mm. Depending on the resolution of your meter, and the resistance scale you are using, the resistance of the lomc may be low enough to appear to be a short even though it is not.

Regards,
-- Al

Would demagnetising the cartridge help? There is a way to do this manually using the RCA's of the tonearm across each other (30 secs.),first one way then the other,the centre pin of one crossing the pin and shield of the other.Also it is not uncommon for there to be a difference in channel output even in new cartridges.From my position I would demagnetise and then listen to the playback with and without the tweak I suggested earlier.You should hear a clear difference and decide what to do from there.

Normally the Lyra have excellent specs and are robust. Who knows, maybe it fell onto the record or similar and...
Wire
Well, can be possible also, but a wire seldom breaks, I would check the soldering in the RCA plugs.
Don't you have a friend who can loan you a cart? Then you would know it in a few seconds...

Almarg is right,never put an ohm meter across the cartridge coils. I never did this before but after Almarg mention it I took one of my meters and turned to ohms on the low scale and checked the voltage across the leads with my second voltmeter and it read 2.6 volts dc. Not good for a moving coil cartridge.