There is a design fault in the fuel valve selector in the C150/152 aircraft that you should be aware of. Unless the selector is exercised regularly by selecting OFF at the end of a flight, it eventually becomes stiffer to operate over several months and finally seizes up.
Most flying schools leave the fuel selector on at all times and thus the binding or jamming is not picked up. Then if an attempt is made to turn off the fuel selector as in an engine fire or engine failure, it stays jammed on with possible disasterous consequences.
From my experience this defect is rarely picked up during routine maintenance. Or if it is picked up, shoulders are shrugged and the owner refuses to have it rectified as it will cost money. The aircraft then continues to fly in an unairworthy condition.