Before you start retuning Flexi-Capo "fingered" strings first check the finger covering any out-of-tune note by making sure it is seated properly on the string and then try tweaking the note with the finger itself, rotating it more or less to sharpen or flatten the note as required (i.e. adding or reducing the pressure on the string). More often than not you will be able to tune notes perfectly without having to resort to using your guitar tuners at all.