Welcome to the forum. Another real good resource of information is the Yahoo FT500 Ascot Owners Group. They have a "FILES" section that has several articles on how to perform maintenance tasks & modifications.
https://groups.yahoo.com/neo/groups/honda-ascot/filesSometimes the "FILES" won't open unless you right click on them. Here is the "FILE" on Starter issues.
https://groups.yahoo.com/neo/groups/honda-ascot/files/Starter%20Issues/Glad to hear that you have a shop manual. Is it a HONDA Service Manual, or is it a Clymer?
Do you have a good battery that you can use to start the bike? If not, then that's not a bad place to begin. The FT Ascot draws a lot of juice to start, so you need a strong battery. (I don't recommend jumping the bike off of a car battery. Sometimes the car battery is too strong) I like to spend the extra cash to buy a "Made In The USA" sealed AGM (Absorbed Glass Mat) battery. I buy from Batteries Plus.
http://www.batteriesplus.com/t-storeloc.aspxAsk about their "X2Power" line of batteries. These batteries are somewhat expensive, but they are sealed & don't leak corrosive fumes onto your bike, plus they last a long time. I have 4 or 5 years on one. You might want to pick up a "Battery Tender Jr." while you are at Batteries Plus. They have a $10 off sale if you buy a battery & tender at the same time.
Before you try to start the bike, I would remove the sparkplug & squirt some oil into the sparkplug hole. Then place the bike on the center stand, shift into 5th gear & see if you can rotate the rear wheel. This will force the piston up & down while lubricating the cylinder walls, rings, etc. If you can't turn it by hand, then try it with the battery & starter. Beware that oil is probably going to shoot out of the plug hole. After rotating the engine, replace the plug, check the oil & replace it with some new motorcycle specific oil like Hondalube, Yamalube, Golden Spectro, etc. Change the filters & go around performing pre-start checks. Remove the old gas & provide fresh, then try to start it. The FT Ascot is basically a gussied up Honda XR/XL-500 & is a fairly simple bike to work on & maintain.
How are the tires? I'm guessing that they are shot. So you probably need 2 new tires. I like Avon Road Riders & recently bought a pair from Amazon.com for a bit less than $200. There are many other tires to choose from, I just like the Avons.
How is the chain? How many miles are on the bike?
Then work your way around the bike while checking all nuts & bolts for being tight. Grab the handlebars & forks & shake them back & forth, side to side, etc. You're trying to determine if there is excessive play in the steering neck bearings. Do the same with each wheel & the swingarm pivot. Everything should feel firm & operate smoothly. No clunks or binding spots.
I happen to own 2 FT Ascots. One has less than 10K miles on it, while the other has about 29K on it. I have yet to need to service the starters on either one. I don't know if a previous owner did or not, but they are both working fine. You want to avoid using the starter any more than is required & don't crank on it endlessly. The FT Ascot has a carb with an accelerator pump. Every time you turn the throttle, a small squirt of gas is pumped into the carb. This is a great feature for a couple of reasons. When it comes to cold starting the FT Ascot, I use the choke at 100%, plus I rotate the throttle about 4 or 5 times to prime the carb, then I hit the start button. Usually it fires right up without a lot of cranking.
Well, that should give you some form of direction or ideas. Of course you need to give the bike a thorough bath after sitting for so long. Hopefully it was stored inside. Tell your buddy that he has a great bike. I'm sure he will enjoy it.
Good luck
J.