After much shopping around, I finally purchased the Ariens Lawn Tractor 46 at Home Depot in late September 2012. I used it to mow once and did not use it again until March 2013.
After using it four more times, I found that it had problems going up even the slightest slope in my yard (good news: it still moves as long as it is pointed downhill). I started searching the net to see if others may have had the same problem. Sure enough, others found that the TuffTorq k46ba hydrostatic transmissions developed problems relatively quickly.
It seems that Ariens had tried to get by with a transmission that was not was not up for the job. To buy a new transmission would cost around $400 if I replace it myself. If I get bold and take the transmission apart and replace the "motor" in it, I might get by with around $100. It is sad to think that I had my last lawn tractor (Troybilt 20hp 46" deck) for 14 years and my repairs consisted of replacing blades and occasional deck spindles, but now I pay $1500 for an Ariens lawn tractor that did not last even 5 uses before a major problem developed.
If you are thinking of buying a lawn tractor from Ariens, you better check to see if they are skimping on the transmission at your expense of money and time. Someone called this tractor a "throw away item" due to the expense of getting this problem fixed. I totally agree. If I had the money, I would ditch it and just get a different one, but as it is, I will have to see if I can open the transmission and replace the motor in it. The sad thing is that a poorly designed item will continue to fail. The best I can hope for now is that I don't have to spend too many hours on each repair. Buyer beware.