D damper

[Newton Hunt]

When strings are level and one string is muted less than the other
two it is usually caused by one trichord leg being of a different
thickness than the other or one string is spaced differently.

It has been my experience that it is difficult to move a string far
enough to effect muting and if it does work then the problem will
reoccur.

The best solution is to remove the offending damper(s) and using
appropriate pliers (whatever you can find in your case) and gently
massage the thicker leg of trichord to cause it to become thinner. 
Care must be taken to be gentle.  The massage will make the leg a
little longer.  This excess material can be trimmed off with SHARP
scissors.

If this massaging is done while dampers are installed, one at a
time, it is rare to find one that leaks after the job is complete. 
Not always, or course, but most often.

		Newton