what are the symptoms of a bad hydro unit?

Has to be a linkage issue. Bad hydro wouldn't "lurch" when trying to start it. Adjust the linkage, and centering device. It's an adjustment issue.

If you need a service manual to show you how to adjust the linkage, I just went and found one. I can send it to you if you need.

that adjustment info would be great...and it doesn't lurch but it moves forward or at least tries to move forward

so it was the hydro unit, some bad components inside and the local hydro shop wants 1000.00 to fix it does anyone have a better idea? or I am thinking about selling parts

If it is in fact the hydro don't waste your $$$$. Find a good used replacement or a better tractor. You can try the sponsors at the top of the page and member rweaver for used parts.

Get on Craig's list, type cub cadet in the search box on the left and have at it.

I found a used (144 hours) GTX 1054 that suits my needs very well, tons of power from the 27 HP Kohler. now to find people that need parts from a 1320!

Glad to see you found something to replace the 1320. Just keep in mind that the 1054 is a light duty mower. Not trying to bad mouth it but you may want to look for an older Cub say pre 1996 and then sell the 1054. Holler if I can help, that's why I get the big $$$$ LOL.

Thanks for the advice, can you define light duty? I bought this to mow my 5 acres and not for comercial use, will occasionally pull a trailer of limbs or firewood to the back door.

and can anyone tell me what the prefix GTX means versus the other prefix designations

I don't know what the GTX means but those were made to a price point for Home Depot. The Kohler Courage engines do not have a good reputation from what I've heard. If your cutting 5 acres you really could use something more robust. I'll just toss out a couple that I'd be looking for starting with the
Super GT's
1772 Kubota D 640 diesel
1782 Kubota D 640 diesel
2182 Kubota WG-600 gas
2084 Kohler CH20
2284 Kohler CH22

GT's
1864
1863
1641

2000 series
2180
2185
2186

I'm not crazy about the 2000 series stuff. Just my 2 cents but I'd look for one of these and then resell the one you just bought.