I just added a dual tail motor setup to my CP pro and all was working good. I then added a HH gyro and after install did all the testing and it seemed fine. When I put it on the floor to try a hover test, I lost the tail rotor completely. Neither motor will spin. I am getting 11.35 volts to the motors and the gyro has power, but no tail rotor. Any ideas?????

When you say all was working fine, I assume you mean both motors turned and the tail blade spun normally, so the motors arent fighting each other and the gear isn't too tight.
Now you say you are getting voltage to the motors--are you measuring this at the motors or at the connector at the 3-in-1?
If you are measuring at the unit I'd say check the wire in the tail boom. If at the motors, I'd say the motors are fried. They aren't very good motors to begin with.
Try testing the motors out of the circuit to see if they spin.

And when you want to really improve your performance try the DD system.
I put some test results over there:
http://www.rcuniverse.com/forum/fb.asp?m=5079804

Is it really possible that the tail motors BOTH burned out? one was new, but I did discover that one of them was bound up. Bad bearings in the motor maybe. I have another motor sitting around, but that was removed for another reason ( I can't remember why! ).....
Oh yea, i was measuring the voltage at the motor, not the 3 in one....

Sure, if one is binding and the other one is trying to push it, they can both go south in a hurry.
And they can fail in sneaky ways. I had fits over one that would run, it just wouldn't run fast enough, it topped out at about 1/2 rudder stick travel and wouldn't go fast enough to keep up with the gyro. I thought the 3-in-1 was bad, I thought the gyro was bad, I thought my radio programming was bad, everything was suspect but nothing worked--until I replaced the motor.
I'm using the DD tail now and it works well. It's a better quality motor, for about the same price as the stock eflite motor.
The current draw shown in the pics on the other thread seems high, and you do get a bit shorter flight times--I get 10 minutes on the stock battery in normal mode, 15-16 minutes on a 1320 mAh battery in idle-up flying hard.
It works fine with the stock 3-in-1 but I took mine out and am running 2 GWS ESCs + G90 gyro instead. Works fine this way too and the GWS mosfets barely get warm.

I guess I'll hit the LHS tomorrow and pick up a couple tail motors. I thought the dual system would save motors, not burn them up !!!!!

If you are going anyway, you might look for the GWS motor, GW/EDP-50H or the CN-12 will work, and the prop and adapter GW/H001-FD5002-030B, and there are several other props that will work.
No mod to the tail is needed, except you might have to "drift" the screw holes over a bit.
You already have the heatsinks! But GWS makes one that fits better.

Much better performance and quieter than the dual system.

Yeah, it's a good idea to buy a couple of brand-new tail motors whenever you upgrade to a dual tail motor mount, even if the previous motor isn't very old... It doesn't take long at all to wear out a single motor on a LiPo-powered HH gyro setup. If one motor seizes or otherwise locks up, then it will quickly overheat the other and then both motors are shot. But if both motors are brand-new, then both will wear out relatively evenly and you greatly reduce the risk of frying a good motor because one of them was old.

I have a dual motor setup for my CP Pro tail and I bought two new tail motors for it, and I've run it well over what a single motor is expected to live. It rocks! Buy two motors and see if that gets you back in the air, and if it does then you're not gonna be buying tail motors for quite a while.

I fried both motors in a dual set up all at once. The first went and dragged the second down with it. The bearings bound up and the 2nd motor had to spin both. The entire housing was almost too hot to touch after I figured it out. It flew ok but the tail didnt have much authority. By the way you never specified which HH gyro you installed.

Just try the DD system.
It works. Don't believe it?
Look at this:
http://www.raymondstacy.com/pics/bladecp.wmv

(18.7 MB--worth the wait)

Here is an [link=http://bladecprepair.com/man_tr_dd_conversion.html]article[/link] with part numbers and instructions to change to a direct drive setup.