Performing routine annual maintenance on my Echo hand-held leaf blower,
I discovered that last spring, I mistakenly installed a spark plug one
heat range hotter than specified. The blower was used plenty with this
wrong plug in it- and the part of the plug inside the engine had a heavy
very light gray deposit on it.

Wonder if that did any permanent engine damage or shortened its life€¦

--
I dont mind a reasonable amount of trouble.
- Humphrey Bogart