@knightowl12 ,Jeffrey, You may have to disassemble the Dremel(link below) which will allow you to access the shaft which you can put vice grips on to hold the shaft while using pliers/vise grip on chuck to loosen collet(if able put a couple drops of penetrate oil to run down bit to collet jaws for 30 min. before starting the repair).
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@knightowl12 ,Jeffrey, If collet lock button not holding sufficient, you may have to disassemble the Dremel(link below) which will allow you to access the shaft which you can put vice grips on to hold the shaft while using pliers/vise grip on chuck to loosen collet(if able put a couple drops of penetrate oil to run down bit to collet jaws for 30 min. before starting the repair).
@knightowl12 ,Jeffrey, You may have to disassemble the Dremel(link below) which will allow you to access the shaft which you can put vice grips on to hold the shaft while using pliers/vise grip on chuck to loosen collet(if able put a couple drops of penetrate oil to run down bit to collet jaws for 30 min. before starting the repair).
[guide|42690]