Thinking About Buying a Ban Jammer
Instruments- discuss specific features, luthiers, instrument problems & questions
I built my own banjimer. It's fine to play, and not a particular bother to others. If it does bother someone, just play softer. :) You may end up not wanting to play it like a regular MD, there's something about them that leads you to expand your horizons. You don't have to get a 'custom' MD, most all makers have standard models you can choose from.
As far as your current MD, a piece of credit card under the nut [1st] will probably help and let it be more or less playable. Ken gave the fix/trouble shooting on them. It being that old does not necessarily mean it's cheap or poorly made, especially if built by a recognized early builder.