My 110 has a fixed (welded) bracket, factory sealed ends on the cable, and no way - other than to cut and reform - the tensioning spring. There is no adjustment for which I can readily see. The new 42" belt was installed in the manner in which the packaging on the belt indicates. The belt continually falls off - as did the former belt, which was changed to prevent this.
Is 42" the right length belt? How do I tension in this case?
is it an original JD belt bought from a JD dealer ?
If it is only 35 hours old then I would be contacting the dealer where you bought it from because it might be a warranty job.
Belts are not usually covered by warranty because there is no control over the way the mower is used or abused and they are a normal wear item just like tyres on your car.
If you bought it from Lowes tough luck, all they know is how to process your payment.
What you are writing makes little sense to me
the 100 series JD lawn & garden tractors use belt no # GX20072 which is 103 + 7/8" long
The same belt is used on
100
115
120
125
135
D100
D105
D110
D120
D125
D130
E100
E110
E120
E130
L100
L110
L120
L130
L130
LA100
LA105
LA110
LA115
LA120
LA125
LA135
So unless this is a totally new design I have no idea what you are saying.
Please post the numbers from the ID tag which is generally on the left side of the mower
I added a teflon lined collar behind the cable endcap, in front of the fixed cable mount on the mower deck, that eliminated some of the slack. I found and reinstalled the two pulley covers, which are made with belt "rub rails", that definitely assist in keeping the belt from disengaging. The mower still functions the same, cuts better, doesn't "give" (slip) when encountering heavy grass, does not disengage, and I am satisfied. The belt is a GX20072, which many on-line parts suppliers describe as a 42" belt.
Good news you got it going & installed JD OEM belt. I always check oil level on dipstick before each use & walk around mower giving it a quick look over, kick tires etc. before getting on seat & starting her up.