Patio Door Runners
Your sliding patio door may glide smoothly to the touch.
Alternatively it maybe stiff and heavy to open and close, and/or may run noisily. The lock might not operate easily.
Do these problems sound familiar?
Then the answer probably lies with the wheels or runners hidden away underneath the door. These suffer a lot of wear and tear, especially in salty and/or dusty environments. Bearings can seize up, and/or wear out. The result is the stiff or noisy operation, also possibly causing the lock to be out of alignment making that stiff.
The cure is at least to check the function, clean and lubricate the wheels and adjust if necessary. It may be necessary to replace them, but the result will be well worth while and will save more expensive wear and/or failure later.