Yassir! Yankee ingenuity! And, thats how a lot of us have to fix our cranky old lawn equipment! But, the fixes we use, are done by us--for us--and can't be used on somebody else's equipment. Safety, don't cha know?!

Is the air gap adjustable on your clutch? Could be too much gap and drawing higher amps to pull in? Usually about .012

***"shorting out at the H_B connection"***
H-B is "open circuit", so the H-B path would not create any type of "short or extra load" unless there was a defect in the PTO switch, and since you have tried 4 new switches, that sould pretty much eliminate the PTO switch, per se, as a suspect. I would be looking at finding a corroded terminal somewhere in the circuit between the A1 terminal of the key switch over to the B & E terminals of the PTO switch and over terminal 87 on the Operator's Presence Relay AND then over to terminal 30 of the OPR and then on to where terminal 30 wire finds its ground connection. Corrosion has a nasty characteristic of creating high electrical resistance which can damage components because the high resistance causes higher amp draw through the entire circuit. If you do not discover corrosion on any of the terminals mentioned above, check for a chafed wire or other defect in the circuit between term E of the PTO switch and the wire LEADING INTO the PTO clutch (under engine). A "short to ground" of the wire in that part of the PTO circuit would lead to a high amp draw (or an outright "dead short") which might be reducing the life of the PTO switch, but you should also be blowing the fuse (unless a "too big" fuse has been put into the fuse holder!). Note that a damaged or chafed wire (short to ground) anywhere in the circuit leading AWAY FROM (ground circuit) the PTO clutch, (including the circuit that leads from 87 of the OPR back to the "foot brake & clutch switch" ) would only result in the clutch engaging without the OPR being activated.
If you find any corroded, or "burnt" spade terminals in any connector plugs, these need to be removed and replace with new ones (they can be "released from" the plastic plug with the appropriate tool and the right technique. Substituting a separate switch will not solve the problem if the underlying cause of short switch life is not found and addressed properly. The switch you select as a separate switch might have enough ampacity to melt some wiring in the chassis harness instead of failing like the OEM switches have done. It is also possible that the PTO clutch itself is drawing too much current. You can e-mail me for a PDF on those tests if you like.

Here is a link that might be useful: 917.272248 OM

***"Funny thing when I took it in for a new one it worked on the new mowers"***
That right there could indicate that the problem exists in the metal spade terminals of the plastic plug that connects to the switch, and not the switch itself. Have you been using an ohmeter to test these switches or just using the "swap switches" technique? If using the swap switches method, you are ignoring the likelihood that pluging up a new switch did nothing more than "scrape away" some burnt metal in a damaged spade terminal. That action COULD MIMIC the results you would get if the former switch had actually been bad, but since the terminal is already faulty, the "fix" would be short lived. Soon, that tiny spot that re-established continuity, will burn up too, and then you are right back to "NO PTO action". That could explain why the alledged "bad switches" still work when you take them back to the source and they tell you the switch is still good. A truly defective switch would not work on one machine, but not on another. It all boils down to "test.....don't guess". So, post back with any results or comments.

Dang, mownie, you always impress me with your clear and detailed suggestions. Wish I had you for a neighbor.

Hey thanks for all the ideas, yes I have used my test meter to see if the switch was working before I took it in the first time, Like I said the HB part was bad, when I got my first new switch, I checked to see if it was ok, and it was. The old switch with the bad HB would still run the blades on a new machine. Very strange, One guy at sears told me that some of the switchs were bad and they changed the wireing to it, cheaper than making a new switch, thats why it worked on the new machines, All the connections look good and checkout ok. The clutch will engage when I put power to it, and the fuse in the line doesn't blow, so I assume that there is not too much draw from the clutch. The wires don't get warm on any of the ones, like there is too much draw, except at the pto switch itself. Sounds like an old Chevy I had years ago, time to sell it and move on. I think I will try the wire from the bat. with a switch and fuse to the clutch first and see how long that works.

Hey, I just checked my notes for the bad pto switch and noticed that I had wrote HB as bad, when it was really the B+E part of the switch that keeps going out. Sorry about that, I wrote down the wrong connection of the switch which keeps going out. It's the B+E connection that is going out each time. By the way, what fuse should I use if I was to run a line right from the bat. to the clutch? Don"t want to spend 250$ for a new clutch if I don't have to.

***"what fuse should I use if I was to run a line right from the bat. to the clutch?"***
With the load of the PTO clutch only, 10 amp will be sufficient. That way, if there IS something in the rest of the circuit that is creating the heavy electrical load that is causing the repeated failure of the PTO switches, it will blow the fuse before it damages the wiring.