Go and get a new one from B & longQue then you tight fisted old sod.
Qualcast 'over mower thing for about 50 snotters IIRC. Doesn't have blades that need sharpening, just bits of plastic wingy cutty things that you replace every few times of use, and you get a bag of them for about a fiver.
Dead simple to do....for most.
I'm here to help. Demo at 'The Swamp' if you want, but it'll cost you a pint.