I'm worried that the tool has been compromised. The instructions say to take the drill to a repair shop to have it cleaned and lubricated after use. I would like to know how to clean and lubricate it myself.

The sense I had after the conversation was that one could not grease the Bosch, or grease the DeWalt, and unless extensive use was made of the unit, or extensive grease was applied, it wouldn't make a big difference.

Your tool was properly lubricated before leaving the factory. In from two to six months, depending upon use, take or send your tool to an authorized service center for a complete cleaning, inspection and lubrication. Tools used constantly on production jobs will need relubrication more often. Also, tools “out of service” for long periods should be relubricated before being put back to work.

All bits get warm during use, particularly hammer use. If there is an abundance of grease in the chuck, some may get warmed up and migrate out. Even without an abundance of grease, some may weep out.

I own a hammer drill (DeWalt d25263). I was using it today, and everything went well. But as I removed the SDS chisel bit that I was using, I saw a good bit of grease on the shank of the bit. I've never seen this before.

So I asked at the (now former) local DeWalt service center. The tech there told me that I should continue to put a light coating of grease on the bits, particularly during times of heavy use or after times of relative non-use.

I decided to grease my DeWalt (absent instructions from the manufacturer) and continue to grease the Bosch. I use a synthetic high quality chassis grease.

I looked for videos on YouTube but didn't find anything that was helpful. Can you please tell me how to clean and lubricate a hammer drill?

If you like, dab a little common grease in the chuck on occasion. There's a lot of slop (movement) in that type of chuck, and friction can heat things up if it's totally dry.

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She also said that more than one Bosch rotary hammer user has failed to grease, and they notice that the chuck is a little dry when servicing the chuck.

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DeWalt instructions never mention adding grease to the bit. When the DeWalt was factory new, a bit inserted came out with a light coating of grease.

I have both a Bosch rotary hammer and a DeWalt rotary hammer drill. The Bosch instructions say to apply grease from time to time on the bits. Bosch even includes a small tube of grease.

The simple fact is that it doesn't need periodic lubrication for the casual user. It would be different if you were a professional drilling dozens of holes every day.