I have a 1983 Trek 720 I did a resto-mod on. The headset is a Tange MA-60 1" threaded headset taken from another Trek. I had a bike mechanic set the top and bottom on my head stem with a headset press. I did the rest. I've been doing lots of brake testing and when I really really reef down hard on the front brake, sometimes I get a weird sort of soft 'cunk' like the fork is wobbling in. Not really wobbling, but there is a feel of something. It might be the brakes themselves, or the headset. If it's the headset, I'm guessing either my headset is not tight enough, or its pair of caged bearings is suspect and should be replaced with loose ball bearings. Any suggestions?