Does the new switch have the markings shown in the diagram Star posted in reply # 7
If so make 3 jumpers with a male at both ends
Unplug the engine plug to avoid accidentially putting power onto the kill wire
Now according to the same diagram this mower runs the power to trigger the starter solenoid through the two lap bar switches via the green wires
1) So unplug both lap bar switches and jump the wires at the plugs then jump the B & S terminals at the key switch engine should crank .
2) IF fuse does not blow then jump B & L terminals , hour meter should start counting nothing else should happen
If fuse does not blow then plug the key switch and try both positions
IF fuse does not blow one of the lap bar switches is bad or the plug has a bare wire or even spiders web shorting it so plug one in and turn key then the other till fuse blows .
IF the fuse blows at step 1 then the lap bar switches are OK & the green wire has a short some where
OK. I had some time today to look at this. Here's what I did:
1. Disconnected engine plug. Turned ignition to ON. Fuse blown.
2. Jumpered lap bar switches and Ignition terminals from B to S. Engine cranks. Fuse OK.
3. Changed jumper on Ignition switch to B & L. No hour meter display. Fuse OK.
4. Removed jumper on ignition switch and plugged it in. Turned switch. Fuse OK.
5. Connected engine plug. Sat on seat to avoid any issue with kill switch. Turned ignition switch to ON. Fuse blown.
4. Disconnected hour meter. Sat on seat. Installed ignition switch jumper from B to L. Tested voltage between hour meter positive to screw on solenoid. 12 V.
5. Connected engine plug. Sat on seat. Tested voltage from hour meter positive to hour meter negative. 8 V.
6. Disconnected engine plug. Tested continuity between hour meter negative and engine plug terminal. Had continuity.
7. Followed green wire from opposite side of engine plug back to engine and disconnected. Tested continuity between engine plug terminal and the end of the wire. Had continuity.
8. Reconnnected engine plug and green wire to engine. Sat on seat. Tested voltage from hour meter positive to hour meter negative. 8 V.
9. Disconnected green wire from engine and moved it to the solenoid ground terminal. Sat on seat. Tested voltage from hour meter positive to hour meter negative. 12 V.
Also, I _think_ that I would need to have the engine plug connected for the hour meter to work. So I think that item 2) would never show anything at the hour meter. That's why I connected the engine plug and sat on the seat.
I assume that this means that the ground connection to the engine is bad. Tomorrow I'll see if I can clean the engine ground terminal and tighten the connector on the wire. When I removed the wire it seemed a little loose on the engine ground terminal.
In the diagram, with the wire (green) from the engine plug to the solenoid ground, it read 12 V at the hour meter. With the unmodified wiring (purple), it read 8 V at the hour meter.
I'm still not sure why this would cause a blown fuse...
Hopefully this is the issue, or I've provided enough information for someone to tell me what to try next.
Thank you all for your feedback. I feel a little lost here, and it's awesome that you guys took some of your time to help me out. I really appreciate it.