HenryQ

Hi, I have a Makita HP1621F which is a keyless 1/2” hammer drill. It’s a nice drill, but the chuck has finally failed on me. It will tighten, but after a few minutes use it loosens. First question: does this mean I need to replace just the chuck or might the problem instead/also be with the spindle, compression spring, ball bearing, retaining ring or helical gear, all of which have a bearing on the chuck (see the parts diagram at: https://www.ereplacementparts.com/makita-hp1621f-hammer-drill-parts-c-97_16247_1585.html) I’d hate to throw it away for want of a chuck. Unfortunately, the Makita replacement chuck, even on eBay is pricey ($50 new). I don’t want to spend a lot of money on a new part for an old tool which itself has an uncertain life. It’s only worth getting a replacement chuck for not too much money. So, I’m wondering if any forum readers could suggest an OEM or other chuck that would work in my Makita HP1621F. Note: the description on the drill itself, describes the drill as a 5/8" drill. However, all the descriptions of the drill I've ever seen (on eBay, for example) list it as a 1/2" hammer drill. The Makita replacement chuck is Part Number: 763192-3. My thanks in advance for your suggestions and help. I will very much appreciate them.