depends....if the crystal needs replacing ,pop a new one in...if the dial needs a gentle light dry brush to get specks of old lume, foreign bodies etc off then that's ok too. Despite having the gizmos to remove hands and put them back on, I wouldn't do it on an Omega as I'm clumsy...I practice on old junkers and know my limitations. Any work required under the dial of a Dynamic and it's off to the Watch Doctor.