When viewing a property do not be afraid to try “all” the UPVC doors and test that the handles operate smoothly and that the key turns with little resistance, always ask to see all doors opened and try them out. Dont feel awkward about this, it is your money you are spending should you go on to purchase and a fault found at the stages of a viewing can save you a heap of problems when you move in. Should a vendor take issue with this then ask yourself what have they got to hide? Its a reasonable request! I have decided to post this advice as several times I get asked to visit properties once new owners have moved in and often I get asked “can you open this UPVC door, we were never given a key”. This immediately raises an alarm with me as almost always this results in a broken Multi Point Locking mechanism and the vendor / seller has hidden it from the buyers hence the keys are withheld and invariably results in a lot more than a simple door opening and cylinder change. I have also been asked several times for an inspection or cheap fix of a UPVC door by people who have just sold their property, I arrived at one just this week and a mechanism in set of French doors was seized in the open position. I quoted and as is unfortunately often the case the Vendor blatantly stated that they would leave it to the people moving in! Not honest behaviour but unfortunately that is the mentality of a lot of sellers who have no desire to spend on a property they have sold. So remember, that little bit of effort and investigation at the point of viewing can put the problem back with the who it belongs ie the seller.