I have an older Toro 22" Recycler Model 20218, ser. 1034942. The motor is B&S 5hp Model124702, Type 311501, Code 91031525. I'm trying to clean up for mowing season. On starting, it makes a loud noise that sounds as though the blade is contacting the mower housing. There is no sign on the housing or the blade that it is hitting anywhere. The blade is very tight and straight. When I remove the blade the mower starts and performs normally - no noise. Could it be a compression problem that appears under load? I only ran the blade for seconds as the noise is very evident. Any help is appreciated - my daughter cannot afford a different mower.