Symptoms
- Crank handle spins without opening the window
- Crank feels loose or wobbly
- Grinding sound when turning
- Window won't open or close at all with the crank
Likely causes
- CommonStripped gear teeth inside the operatorThe small gears in the crank mechanism wear down after years of use.
- CommonBroken or disconnected scissor armThe linkage that pushes the window out can crack or pop loose from its track.
- PossibleDirt or dried grease jamming the mechanismOld lubricant can gum up and stop the gears from turning smoothly.
- PossibleStripped mounting screws letting the operator shiftA loose operator base changes the gear alignment.
What to do
- Open the interior cover (if present) to see the crank operator and scissor arm.
- Turn the crank slowly while watching the scissor arm; if it doesn't move at all, the gear inside the operator has likely stripped.
- Check the mounting screws holding the operator to the frame and tighten any that are loose.
- Clean visible grime from the scissor arm track and apply a fresh coat of window-mechanism grease.
- If turning the crank does nothing, unscrew the operator from the frame and take it (or its model number) to a hardware store or order a matching replacement.
- Disconnect the old scissor arm from the sash, install the new operator, and reconnect the arm to the same pivot point.
- Test opening and closing fully several times before reinstalling any interior cover.
Tools and parts
- Screwdriver
- Window mechanism grease
Casement window crank operatorSearch: “casement window crank operator replacement”
When to call a pro
Call a window repair pro if you can't find a matching operator for your window brand or the scissor arm attachment point is damaged.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.