ELT-Phone ST-888 Problems. I know its a long shot.

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I just got this ETS payphone and upon plugging it in it worked fine. I toggled the lock switch on the back of it and now it does not seem to work as it once did.

I took my multimeter and could not find anything electrically important about the switch. I'm thinking that the switch could be the cause of the problem, but I'm not sure.

Any help at all would be greatly appreciated

I should also mention that when I lift the receiver off the hook my other telephones show that the line is currently in use, although this phone does not have a dial tone.

I checked the switchhook assembly.....Nothing special....