Check out pictures here: http://pg.photos.yahoo.com/ph/ahug030/album?.dir=1b00

As you can see from the last picture, one of the heads is in bad shape (compared to first picture), also the cylinder has some minor surface 'rat bites' on it that don't come out too well in the photo. The barrel of the offending head has a small gash on its mating surface - could this have caused the erosion of the head? I need to figure out what caused the problem before I go out and spend $$ on a new part that may be damaged in the same way.

The eroded head looks like it is from a different model by looking at the parts manual (the top head in the fourth picture across), maybe there is a difference in dimensions that could have been significant...

Thanks for any help guys.
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'87 MC16