Problem validating utf-8

I am having a problem with my WordPress blog at https://www.joewessels.net.

I tried to validate my code and got this response from https://validator.w3.org :

Sorry, I am unable to validate this document because on line 617 it contained one or more bytes that I cannot interpret as utf-8 (in other words, the bytes found are not valid values in the specified Character Encoding). Please check both the content of the file and the character encoding indication.

The error was: utf8 “\x92” does not map to Unicode

Any suggestion(s) on how to fix this? I cannot figure out how to look at the code, for starters, which seems to be my problem.

Thank you, in advance, for any help.