I just inherited (borrowed-ish) a Trimmer lawn mower 20" from my grandfather-in-law. It will probably end up being mine as I don't see him using it now that he's in a house that has fescue. At 90, he's still mowing his own lawn which is impressive on its own. It's a 1985 and we were able to get it up and going. I just sent it to the shop to have the reel sharpened and the engine looked over because it sat for some time (15 years) and has some parts that need to be replaced. The guy at the shop mentioned that I may at some point want to get a 7 blade for the mower. They run about $300. My question for you all is what is the benefit to a 7 blade vs a 5 blade? Also, is it worth the $300 to invest in a mower this old?