HOW TO FIND SPECIAl MOD parts

Good morning, I am new to the forum. I'm 75 years old and love getting ATVs back to usable condition. I particularly like the 2006-2009 Arctic Cat 250 Utility. I currently own 6. The 2006 I am working on only has reverse and low gear. The "drive shaft" in the transmission is completely stripped where the high gear would mesh. Has anyone on here replaced the shaft. I'm told I have to split the case. I was hoping that someone on here could let me know how hard it will be. I already have it stripped down to where the shaft coming in from the clutch side is the only thing left. I was hoping I could just remove the driven clutch and drive it out from there. Directions say different. Any help would be greatly appreciated.

I'm working on a 2002 Polaris Sportsman 400 with shift indicator problems. The indicator panel only will show Neutral and Reverse. If it's in High or Low, the indicator will show "R".
I have replaced the three position indicator switch on the transmission. There is also a two position switch on the tranny that I didn't replace. If anyone is familiar with this problem, please let me know what I need to do. Any help is greatly appreciated!

Just picked up a 2025 Yamaha Kodiak 700 fixing to do a EPI Clutch mod to it since I dropped bigger tires on it !! Air box , exhaust , and programmer next ! 

Hey everyone,
I’m having an issue with my 2021 Polaris Sportsman 570 – the engine keeps stalling after running for about 10–15 minutes. I’ve checked the air filter, spark plug, and fuel lines, but can’t seem to find the root of the problem. It starts up just fine, but then loses power suddenly.
Has anyone experienced a similar issue with this model/year? Would appreciate any advice or troubleshooting tips you’ve tried that worked. Thanks in advance for your help!

The clutch engagement on my 2021 cforce 400s was approx 2700 RPM, very abrupt/not smooth.   I obtained a "kit" from RNG consisting of a blue painted spring (spring force unknown) with 12 gram weights, as measured on my postal scale.  Installation was easy; 18 mm and 30 mm (not 32 mm as seen on other writings) impact sockets for clutch housing removal.  The resultant clutch engagement was still up to approx 2500 and very abupt/not smooth.
 The original spring was labeled p/n 0951-1021 (specs for spring force 300/1600) with 18 gram weights.
I called RNG who told me the kit should work fine for my ATV, but that wasn't the case as I found.  
The RNG spring was slightly longer than the stock spring, but felt slightly easier at initial downward force but had more resistance than stock as I continued to push down.  RNG would not tell me what the spring force was.
I then tested the clutch with the RNG spring and the OEM 18 gram weights with the resultant engagement RPM of about 2050 RPM, a little smoother engagement but still not good.
I am really struggling to get any answers on the best combination of spring / weights to achieve a smooth engagement of maybe 1800 RPM.  Note; idle RPM is approx. 1600.
I have searched all the forums and cannot find good information, and RNG appears to be not willing to share information.  What gives here?  Anyone with experience to share?