Tried to start my 1972 RT2 360 with no luck. I checked and had no spark so pulled the flywheel cover off and checked and then cleaned the points. I now had a nice strong spark. The next day before trying to start I checked for spark and I again had no spark. Then I noticed I had left the ignition key in the on position from the previous day.  Could I have damaged the Ignition coil? I checked the points and even cleaned a second time but still no spark. 
Anyone know where I could get an Ignition coil. 
Thanks 

The way these are wired from the factory the coil won't be damaged by leaving the switch on. The engine ignition system is separate from the battery charging system.

If the wiring is original or mostly original there is a strong possibility of a poor electrical connection at a "bullet" connector or ground connection. Another possibility is a short circuit to ground in the ignition coil primary (points side) circuit.

Also, if the sparkplug cap is original there could be an issue there as they typically contain a resistor that can become an open circuit on the coil secondary (spark plug) side.

Original coils are surprisingly reliable.

As mentioned above, the original spark plug cap has a resistor in it, so make sure you're not using a resistor spark plug. Did you completely run the battery down? I've heard that if you happen to stop with the points closed and leave the key on, it might harm the coil, but I'm not sure about that. You can use a multimeter to check the coil for correct resistance.

Leaving the key on with a magneto won't burn up the points or ignition coil.  

(The battery ignition on the electric start AT and DT125's can be damaged by leaving the key on)

A bad rectifier on your bike will allow the battery to drain through the magneto coils which "could" damage them, but not very common for that to happen.  

My guess is the points aren't really clean, I'd clean them again.  What process are you using to clean the points?  For some reason, successful points cleaning seems to be a lost art.  

Anyone mention try a new out of the box spark plug with a gap set to 20 thou. Can run the mag black straight to the coil if you suspect problems in the loom or switch. Be careful not to earth the short black on the mag loom if it exists not far up from the mag. Has a female cover & just useful as a timing checker. Just branches off the main black from points to main loom. If you had the flywheel off then be sure to tighten it good--better than good.

Thanks for everyone's input. Spark plug is a B8ES though it had a B-9ES which the manual calls for. Just happen to have a new B8ES. Will pull the tank and check wires. Have not pulled the flywheel but have a new set of points and condenser I might put in. MARKT would appreciate your points cleaning method. I was using electrical contact cleaner, putting some on a paper index card. Then blew them off. Have used point file and 400 grit wet sandpaper.

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