Can you clarify is the machine actually skipping stitches or are you getting an unusually long stitch length in just one area?
You can tell the difference by if there is a needle hole in your "skipped" stitch and needle just isn't picking up the bobbin thread? A true skipped stitch the needle goes down but does not pick up the bobbin thread.
If you are just getting long stitches and no needle hole in the long stitch area it is not true skipped stiche. If in just one area of the rack you definitely have a problem with your stitch regulation and because it is in the same spot I am thinking your rack is out of square or out of level in this area causing the encoder to not "read" your movements properly. Especially if you are getting satisfactory stitch quality everywhere else.
Check every inch of your rack with a steel tape measure and a carpenter's level. Especially between your front and back rails that the machine carriage travels on the entire length of the rack. If you have any variation, even a fraction of an inch anywhere between those rails this could cause the encoders to not read properly. Additionally, if the rack was not initially set up correctly (perfectly square and level) your 5 years of use could have torqued and warped one or more of your rails. Has your machine always glided virtually effortlessly on the rack or do you have to muscle it around? Do you feel pull or drag in one section of the rack? These are both strong indications of the rack being out of square or our of level. Can you put your machine head anywhere on the rack and let it go does it stay put or does it start slowly creeping towards one side or the other or towards the back or front? this is Out of square/level rack.
You need to pinpoint if this is a stitch regulation problem or a needle not picking up the bobbin thread problem. Another test is to put scrap fabric on and run your machine unregulated at varying speeds, concentrate on your area of "latitude". If you get fine stitch quality unregulated then you have a problem with your stitch regulator and 5 years ago is about when TL was having all their problems with electronics. I have heard some people solving the problem by putting weights on the bar that carries the encoders so more pressure is exerted on them as they travel the rails and they don't "miss" spots. Others never solved the problem and I am sorry to also say I have not read good things about the lizzies. Neither customer service nor quality of their SR and electronics.
If these are true skipped stitches, but only happen in one spot I have no advice for you. Usually true skipped stitches will happen anywhere and everywhere and are related to timing and needle bar adjustment. You can try adjusting your needle bar height. That often helps. In my experience the only time I have had a problem with skipped stitches is when I had to reset my timing and I got the needle bar height wrong. You can throw that out of whack by hitting an exceptionally bad area of bulk, a blob of hard glue or hitting a ruler template when doing ruler work. Innova has a you-tube video for how to do it but I don't know if a lizzie is set up the same. You may have to find a local dealer or sewing machine repair guy that you can get the head to if you don't want to try doing it yourself. Hopefully your manual covers it.