I work with some people who install & remove CRTs (from slot machines) and they had a technique for discharging them. I’d suggest taking it to a TV repair shop and offering them $5 to discharge it for you.
One of these coworkers of mine said (urban legend brewing here?) that not only can they hold a charge for a while, but there was one occurrence when a monitor unit that was discharged was put on a (metal) shelf for several months, and it built up a charge again over time, from transient & ambient static electricity. To the detriment of the technician who was sure that the (electron) gun wasn’t loaded 