One Pipe system - water hammer/lots of water from vents

LG

I a homeowner with no experience.  I have a one pipe steam system powered by a Weil Mclain boiler.  I have had problems with the system off and on over the entire eight years I have owned this house.  At different times we have water hammer and large amounts of water coming from the radiator vents.  We have re-pitched the radiators, replaced the vents, had the system looked at by numerous heating contractors.  No one seems to be able to make it work right.  However twice I had to replace the inlet valve which was apparently leaking and overfilling the boiler (had to figure this out for myself).  After that the system did quiet down but that was several years ago.  Last year I had water coming out of four different radiator vents.  I'm talking a lot of water.  Enough for it to drip through the floor on the second floor and into my kitchen.  Since then one of the worst radiators has been removed and replaced by hot water water toe kick radiators (which work great by the way).  After that I had water coming out of only three radiators.  I just had the boiler serviced and the technician could only offer to close off the worst radiator valve.  He did this and miraculously I now had no more water leakage problems. Only now I don't have heat from a major radiator - the only one in my DR.  So I opened the valve again.  Now I have water spewing out of the vent in that radiator - enough to fill a baking pan to overflowing each time it cycles on.  Interestingly I don't have any water coming out of the other two radiators any more.  The water hammer is bad enough to wake you up.  Please, please help me.  Any help or suggestions would be most appreciated!

STEAM DOCTOR

Possibilities

1. Poor boiler piping

2. Dirty boiler water

3. High boiler pressure

4. Clogged return piping

5. Sag in main steam line

6. Oversized boiler

7. Partially closed/blocked radiator valve

8. Undersized radiator shutoff valve

9. Poor piping from steam main to radiator.

Just to name a few

STEAM DOCTOR

water level

Forgot to mention that you should check water level in glass. Shouldn't be more then 1/2-2/3 full.

STEAM DOCTOR

other post

Just saw other post. Other posters are right on. Never going to work correctly with current near boiler piping. New heating contractor needed!