You can clean out harmonica reeds fairly easily, if you are gentle enough. You don't really need special tools - a pin will do it. Don't bend the reeds though, unless that reed isn't working and is already bent. If the wood protrudes you can carve it back with a craft knife.

You do need to get rid of some of the 'gunge' from time to time (you know where it comes from!), especially if you draw fairly hard (blues playing) a small piece may fly out down the back of your throat. That's not nice.

I reckon Lee Oskars are better harps and easier to maintain, and you should be able to get a music shop to get the replacement plates for you, although I've not needed any for years.

For people playing straight gob-iron, if you sing in F get a 'low F', which sounds much better that the normal one - it's an octave lower.