I have got to the point of pulling the stem from the middle, BUt it will not come out.. I have pull very hard.. is there a tool or what should I try.. Thanks

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Sounds like a diverter problem, If it is this may help, How to Repair a Shower Diverter on Stanadyne Faucets | eHow.com
If that doesn't get it we need more information, Good luck, Tom