fireplacerepairstone
We have a stone surround to our fireplace. I have noticed stone/cement dust often around it. about a week ago this stone came loose when my son hit it with a toy car. I have now noticed at least one more loose stone. This surround goes up to the ceiling and I want to fix this and strengthen stone that has not yet loosened. I am not sure what to use and should I first remove all old cement?
Thank you 
I am sure that this can be fixed with a thread locker material. There are products available that can be placed onto threads before assembly and then will cure into a very tight joint to keep the threaded fasteners from coming loose.
You can get this at almost any auto parts store. Ask them for "loctite" thread locker.
Before trying to use it clean out the threads in both the ball and on the stem piece. Since you already attempted to use epoxy on these parts it may require extra diligence to clean out the thread grooves. Wash the parts in something like rubbing alcohol and then let dry well before applying the thread locker and reassembling.
Let the locker fully cure before attempting to put torque on the stem and ball assembly.
(Note that I have no affiliation with the LOCTITE brand other than a user).
1) you could use wiremold. They make 90ยบ inside corners. I don't like it but if you have use it then it works. Better off to chop a new box in the wall exactly where you want it.
2) There are several ways to put power wiring behind the planks. EMT, ENT, wiremold...there are others less often used. You will need an extension box on the left power box to run out of.
3) The bricks around should just be a facade but why make it hard on yourself? Just bring the TV mount area out far enough to have the media box behind it.
4) Putting power in the back of the firebox will probably be a major pain. I believe that is firebrick surrounded by other brick. You may need to get a bricklayer in on this. Or at least you should study the construction of fireplaces.
I see other problems here, though. The National Electrical Code requires that no point along the floor line be more than 6' from a receptacle. If you cover the receptacles on left and right will there be other receptacles on the wall line close enough to satisfy that requirement? If not you will have to add them. Also, you can't cover junction boxes they have to be accessible inside the cabinets.
Best Answer
I would not remove any of the cement, except for vacuuming and brushing to make sure the surfaces are clean so the stone can be glued back in place with construction adhesive. Keep the glue far from the edges so it does not show, should any try to squeeze out. Prop it in place until the glue dries, a day or two will do and it will stay.