I saw those finish nails !! Thats why I didn`t ask that it be out of the frame to inspect !! But that is another hint that the artist was not well informed about framing art !! Its always possible that the painting was restretched/tightened up !! I did notice some cracking along the edges that indicate that it may have been,, rather than reused !! But if when it is out of the frame you can tell that there may be colors that just do not belong to this painting !! If so then that is also a possibility but most artists would have sanded and applied a layer of gesso over the old painting before doing another !! And just to clarify what I said,,, I did not mean that the number on the back was the price of the painting,,I meant the price of the unpainted canvas when it was purchased !! I am not sure I helped much on this but if so,, I am happy to do it !! I just wish we could have discovered the artist was a listed one !!
If you try to take it out of the frame ( I don`t think I would as that is the way you found it and it will leave holes and possibly weaken it more) But if you do,, get someone to hold the painting upright and use a small wood block and tack hammer and tap the topmost edge all the way around till you can remove it from the frame but don`t take the nails out !! When done looking at it,, try to put it back as it was !! I think that is part of its history and I would keep it that way if it were me !!