I have a Scandia Evolution 100 R in my bathroom. On/Off handle has gotten hard to turn. Took it apart (handle, cover, retaining nut) but can not get the actual valve stem out of the housing. It wiggles in place, will not turn or pull out. A small notch is cut out on the rim of the large washer attached to the valve stem. Any help on how I get this apart would be greatly appreciated. Thanks.