I have a wonderful old TO-30 that I have been playing with for 21 years. It has always had issues with starting hard, flooding and speed creeping up. I can disconnect the lever from the governor rod to the carburetor and start it and it runs fine. Any suggestions would be very welcome.
There are several springs on the governor control linkage and they all need to be in place and in good condition for the system to work properly. You indicated you have replaced the cork friction disc and the spring on the shaft. There is a good chance you do not have the clamp on the shaft pushed up far enough to create sufficient pressure. The coils on the spring on shaft need to be compressed completely or nearly completely. To accomplish this I find it simpler to remove the air cleaner assembly and then tighten the clamp enough to hold it in place while I drive it towards the dash with a small hammer. It is often necessary to either hold another hammer on the end of the shaft on the dashboard side or tap the end a bit to make sure the lugs are seated in the disc while driving the clamp to compress the spring. Check the final position of the clamp to make sure the throttle lever will move through the recommended arc indicated in the shop and operator’s manuals and not interfere with the oil gauge line, the air cleaner assembly or the battery platform. If necessary reposition the clamp and make sure the spring on the shaft is fully compressed. There are two additional springs which should be checked. There should be a spring at the front end of the shaft where it attaches to the link that connects it to the shaft the drops down to the governor control lever. This spring is a compensator spring, part #181535M1. Make sure this spring is in place and in good condition. The other spring is at the base of the vertical shaft connected to the governor control lever. If this spring, part #180088M1, appears stretched or weak it should also be replaced. The friction disc, part # 180713M2 is still available from MF dealers but the washer and spring on the shaft are no longer available. The washer, part # 180714M1 is still available from many dealers and suppliers as a New Old Stock part. I have several but sadly all my stock is in storage and it may be months before I can get to it. As for the spring on the shaft, part # 180689M1 which subs to part # 826995M1, I have found a spring commonly available from Ace Hardware is nearly identical and works just fine as a replacement.