nibbler

The lifting can occur due to two things both related to forward motion.

1. Hard Snow - The augers are not breaking it up faster than the forward speed of the blower requires so that they lift the front end. More weight might help, a slower forward speed might help, softer snow will help. I've used a shovle and ice chipper to break up really hard stuff and then used the blower to make it go somewhere else.
2. Too Much Snow - The augers feed snow to the impeller which makes the snow go some where else. The maximum volume of snow that the impeller can process is determined by the engine RPM and can be less than what the augers feed it. If there is so much snow coming in that the impeller can't handle it then the augers push it over the top and start to scoop it back in again. This causes a build up of snow in front of the blower. You are "snow plowing". Once the pile gets too big the augers start to climb the pile and the nose lifts up. The only soutions are to either slow down the forward speed or to "blip" the traction clutch so that you move forward in a series of jerks, effectively slowing your forward speed.

If the impeller seems to handle the load and then slows down the throwing you could have a slipping belt.

Given all of the symptoms. I.E. works properly with water not with gas. Its got to be a problem with the float adjustment and the slightly denser water is causing the float to rise a bit higher  to seat properly.

Since it works with water the needle valve/set are fine, the viscosity difference between water and gas won't make a big enough difference to affect the the valave directly, just the float.

Since you have tried multiple floats its not a damaged float issue.

Since you have done the "drill bit adjustment" there are two possible solutions:

1. Try using the next smaller drill size and see if there is a difference. If there is try progressively smaller sizes till it works;
2. There is a tab on the float that the valve stem sits on, try bending it a bit so the valve stem is pushed more firmly into the seat.

Either method effectively does the same thing, it causes the valve to close a bit sooner and therefore a bit more completely when gas is uses.

Try doing a search on "differential" and "traction control" or even "ariens traction control". There has been lots of discussion about this feature over the years.

My current machine has pin lock which is a real pain since I do a lot of turning. Having some way to easily turn is a good thing. At the same time I have a 26" swath and an 11HP B&S and the things generally makes the snow go elsewhere with impressive speed. 13HP sounds like overkill and may make the machine too heavy.

For me easy turning is the most important point for my next machine.

I wonder if the lower pulley ( attached to the impeller) is on backwards. If the top two are in alignment then its probable they are in the correct position.

If you cna't fix it yourself it sure looks like a waranty issue.