DRZ-125L spark plug not seating right

[Doom Rider]

I got a 2009 DRZ-125L, changing plugs, the spark plug is not seating right; it won't screw in all the way, it just gets hung up about 1/4 way in, then when I use the socket wrench to twist it in it won't go all the way in, and the washer just hangs there jangling around.  WTH?  I used a flashlight and ran a sculpting tool around the insides of the machined rings in the engine case where the plug goes in and I did find a bit of a rough patch which shed some tiny slivers of aluminum.  What do I do next?  Is it safe to run (?) or will it even run with the plug sticking 1/4 to 1/3rd of the way out?  Thanks.  

[mjg15]

Don't run it.  Get a metric tap, in the correct size, and slowly clean up the threads.  Use lots of grease on the tap, to catch the aluminum shavings. 

[Doom Rider]

Interesting.  I guess I'm going to learn what a metric tap is and how to use it now.  Thanks for the tip.  My only other option was to send it to the shop and lose a couple hundred bucks or more.  I will try to remember to post how this goes.  

[socalxr]

If it comes to that.  I have a DRZ125 head I'll sell for $150. Plus shipping.