Would this be considered a lamination error? There are 5 coins with various degrees of missing letters and numbers on the obverse. The reverse has no error.
You might be on to something cedarratt. At first the wear looked to be perhaps caused by a slot machine. Looking again the rim appears to be raised with the letters/numbers being somewhat obliterated, which may indicate grease on the die.
cschiefs - These would be referred to as a "struck through" or "strike through".
It is a struck through, and there are different types of struck thru (struck thru wire, struck thru reeding, struck thru grease, struck thru cloth). Struck thru grease is the most common, and really only carries a small premium, if at all.