I bought this exact same model ski and had starting issues too. You can change the bendix without pulling the engine and you can definitely replace the starter with the engine in place. I actually swapped one out in about 30 minutes while the ski was still on the water (the waves made it harder ) If I recall correctly its just three alen head bolts (7mm?) on the back of the starter (PTO side). That said you should definitely remove the airbox, that will give you enough room to work in the area.
Also, if you purchase the ski and plan to ride it hard, consider replacing that air box with from a '99 or older model. If you get a decent amount of water in the ski, the water will enter through the side 'flutes' and get stuck in the airbox... until you suck it into the carbs or take the airbox out and dump the water.
I found this for sale in Atlanta and thought you guys might like the seat cover this guy has. I think it really helps out the color scheme of these skis.
It looks like my timeline for purchasing a 2nd ski has been pushed out a bit. I will be trying to find another x4 (I know this one isn't an x4) sometime over the cooler months as a fixer upper.
I still may try and fix this ski for a couple of extra $.