I’ve had varying success with all of the “popular” methods of removing dried masking tape adhesive. Most leave you still with a cleanup job at best.
The best approach I have found is using ethyl alcohol (ethanol). Even applying over the masking tape if it still remains soaks through the paper backing and loosens the adhesive but the best method is to remove the tape first if you can. Be patient and keep the adhesive wet to allow the alcohol to do its job. Then periodically wipe away the part that has softened repeating a few times until the adhesive is gone. I often get inpatient and use my thumbnail to scrape the softened adhesive to speed the process along. Using the edge of an old credit card will also do the trick.
A word of caution – ethyl alcohol will soften some paints and attack some plastics. It’s best to try it on a small spot to see if the surface is safe to apply the alcohol. I have found the paint used on the cast frame that surrounds the front panels of earlier HP equipment has a tendency to be softened by the alcohol.
A sidebar - when working for one large organization that had its own internal construction department I asked the head painter about what he used to remove unwanted latex paint. He told me that ethyl alcohol was his standard product. I tried it and found ti to be 100% effective at the job.