Please re-read my instructions and check to see if you have spark in the way I recommended. Next, the 10.5 VDC won't give you a very good spark. Do the coil mod I suggested. It is described on
www.wgcarbs.com - You took your coil to someone who looked at it and determined it was bad? Did they have a coil testing machine? If not, they surely have no idea and were only trying to sell you parts. To test the coils, consider they have primary and secondary windings. The way coils fail is that the windings lose their internal insulation and short. To test, put the multimeter in OHMS scale on the lowest setting. With the bike turned OFF, put the leads on the two small lugs where the power and black or green wire is connected and measure the impedence. You should get somewhere between 3.0 and 4.5 Ohms. If the reading is significantly higher or lower, then the primary windings on that coil are in doubt. To measure the resistance of the secondary windings, keep the meter in OHMS scale but put it on 20K Ohms range. Put the meter leads inside the plug caps for that coil... 1 & 4 caps OR 2 & 3 caps and use the probes to touch the metal contacts. You can also pull the wires off (on some types of coils) and touch the contacts inside the coils that touch the plug wires. Anyway, the range here is much wider and will be between about 12K and 18K Ohms. A range above or below will indicate problems with the secondary windings.
Again, there are machines that test the function of a coil but these will be rare, even in a bike shop unless they are very well equipped. If the expert who checked your coil used such a machine, then his diagnosis might be accurate but if not, check them yourself as I recommended.
If you do the checking systematically as I suggest, you will find the problem and will be able to fix it. Good luck.