240 won't start -- any thoughts

3 weeks ago the original Zenith carb was judged unable to be rebuilt and I replaced it with a Marvel on the advice of the tractor shop. It started IMMEDIATELY and started quick and ran fine for about 10 days. Then after a trip in road gear it decided not to start again and this time I updated the ignition wires (made in USA, copper, non-resistor) and the tractor shop also recommended hotter plugs, Champ D21's. Again it started IMMEDIATELY and worked well last weekend and hauled a bunch of field stone.

Here is everything I am aware of for your consideration:
1) smells like it might be running rich and I can't seem to lean it out. I've done the jet adjustments that the shop advised.
2) I don't feel that I have the power I had with the old carb before it died.
3) the idle seems faster than before but I need a flexible shaft screwdriver to adjust it on this new carb and can't find one at my local hdwe store - haven't tried Wally World yet.
4) I'm the guy who committed the sin of using teflon tape on the fuel hose connection into the new carb - it dissolved to my surprise. Hope teflon burns.
6) I'm also the guy who used some extra 2-stroke oil to fill the air breather cup that hadn't been dredged out since Kennedy was president and this unit was new.
7) for the past 3 weeks I've had a can of ISO HEET dry gas in the fuel. This tractor sits outside under a tarp and it is getting cold up here. And the previous owner told me that water in the tank plays hell with this tractor. (He didn't tell me that it needed a new carb.)
8) fuel is flowing well into the carb.

Before I give up and spend money I don't have on calling a tractor service housecall, I wondered if anybody had any thoughts. Everybody tells me that 240s have a reputation as being great starting engines so I am hoping one day to get to that happy place. Getting tired of spending the few remaining non-snow weekends -- when I could be moving rocks and wood -- trying to get/keep this tractor running. Thanks, gentlemen.

I then built a new 30' x 30' shop that wasn't big enough. Took the tarp building apart, reframed it as a leanto on back side of shop. Put on a new tarp. I know a guy that did one with green house hoops.

She was a bit spoiled as on the farm, I had a big tractor with cab had always plowed drivway and yard. A area large enough for milk truck to turn and then some. Now I was just going to be me and Super A. doing the snow. I told her if she wanted a parking area large enough for her bridge club, then my little tractor needed care and attention.

As luck would have it we had close to 5 feet of snow on ground at one time that winter. Super A kept it so she could drive to kitchen door with groceries and could have parked two bridge clubs. I think I could have parked that little tractor in the living room by the time spring came.

I didn't see where you had changed the points. If you haven't done so I'd change the points, condensor, check the rotor and distrubutor cap, then check the timing - aka tune up.

I'd also swap out the coil with a known good one.

Hugh, I don't know what to do about the tarp. I feel I should cover this thing in winter because of heavy snow, a subject I suspect you know something about. Building a 2nd garage or shed ain't in the budget this year.

Thanks again, everyone. I really appreciate everyone's generosity with time and ideas based on advanced knowledge of tractors.

Hal, I am thinking you are right about condenser and coil. Did not replace those yet. Will try that on Monday. I know the coil looks close to original, has been painted over at least a couple times just like the distributor was. On the carb situation, the old Zenith definitely crapped out and the inside parts -- needle valve seats etc. - could not be unscrewed from the aluminum housing to be replaced. I went to the workbench with the old IH-Case guy and am satisfied that he was square with me about that. I am not satisfied that I have the Marvel adjusted right, however, because I don't think I have the power I used to have and keep smelling gas when we are running along with the exhaust in my face.

But that (in my mind) seems to be one problem and I keep thinking that today I am seeing another problem because it started up so well this morning and ran for 11 minutes. But these 2 problems (carb + ignition) may be related. I don't know enough to tell. Thanks.

A spark that just jumps a normal plug gap may not be "hot" enough to ignite the pressurized charge in the cylinder.

The idea of manually operating the points is OK, but actually cranking the engine and checking for spark gives you a more accurate idea of how much spark you have under cranking conditions, which lower the battery voltage.

If the spark jumps the 3/16" gap OK, and the engine seems to be getting gas, try removing the spark plugs, and (safely, away from gas and vapors) heating the tips with a propane torch to burn them clean, and reinstall.

One thing I forgot to add. These plug have about 4 hours on them; put 'em in last weekend. As part of my investigation, I pulled one this morning and it looked dang near brand new.

Allan has inspired me so I will try to post a picture of this tractor taken in a happier moment...not today!

Not that I'm saying for sure that's why it won't start, but if you're really smelling gas, and the ignition system is OK, it sure is a likely possibility.