Hi All,
I recently purchased an Epiphone Les Paul Plustop Pro for my birthday and its an awesome guitar, but on on the G, B and High E string it doesn't stay in tune very well. It has grover tuners which are supposed to be very good. I have replaced the strings that came with the guitar and its improved a bit but it still goes out of tune when I do bends. Any help would be much appreciated!
The two height adjustment posts for your bridge could be sloppy, loosen your strings , remove the bridge , unscrew the two posts. Take some teflon tape and wrap the threads tightly no more than twice. Replace the posts to your desired height . This removes the slop from the posts that cause a lot of tuning headaches. Even if those posts move a little, that's all it takes to go out of tune. Make sure the bridge also is snug on those posts with no string pressure on it. Remember that any slop in that whole assembly will cause tuning stability issues.
90% of tuning issues on a Les Paul (pretty much any Les Paul, from the $6K Gibsons down to the $200 Epi's) are due to problems with the nut, rather than the tuners or the bridge.

Because of the hard angles from the fretboard to the tuners, strings will often get caught by the nut and be out of tune. There are several solutions: have the nut modified by a good tech, have the nut replaced with a teflon-impregnated one, or get some Big Bends Nut Sauce and try that. The cheapest option is to try some pencil lead (graphite) in the slot where the strings go -- it's an excellent dry lubricant.

With new strings, you'll often find that they need a bit of stretching at first.

hey guys I think I will take it back to the shop and get them to set it up properly as have noticed fret buzz on the low e, if that doesn't help them I will get a synthetic bone nut fitted or something