I have an old Sealy GDM-50A/5/B pillar drill and need to replace the chuck as it wobbles a bit. I can’t find a manual for it nor anything online. The most common way on YouTube seems to be to use something like a ball joint splitter and whack it (!) which I’ve tried, but it doesn’t work and I’m not convinced it’s the correct method - or maybe it’s just corroded. Any help gratefully received!