Marquee tool erasing a one pixel line on image

Hello all,

I am using the marquee tool and transform tool to resize several picture frame mouldings. When I use the marquee tool and set it in position, then complete the transform proceedure it cuts or leaves a one pixel line through the colour (in this case black).

Using a spot healing brush on each frame is not really practical because I have 50+ frames to make. I cannot use the option to move the frame over another portion of frame because of the difference in tones on the frame.

Does anyone have any ideas how to prevent the this problem?Please let me know, thanks. Am unsure how to attach image of issue, new to forum, sorry.

Thanks. Jonathan.