When you've been doing it as a business, often time = $$$, and if the customer won't pay the $$$, the repair person isn't going to spend the time.
DH often spends 20 hours or more just cleaning up an old machine before he gets to the oiling and adjusting phase. No way could he do that if he was doing this to put food on the table.
There is always the rule - Cheap, Fast, Quality - you can get two of the three - your choice. The OP is going for the cheap, fast method. Most on here go for the cheap, quality method - and are willing to put in the time required.