I had always figured that the surname Welcheck was an americanized spelling, but it's origin had yet to be identified. Thanks to pilot.familysearch.org I was able to locate a marriage record that has given me the evidence I needed.
I knew from oral family history and census records that Margaret Busch and Stephen Welcheck were married in Ohio in 1887. I did a marriage record search using Margaret Busch, 1887, & Ohio as the search criteria with 'exact & close matches' allowed and got the following result:
Just one more small but wonderful find on the free Family Search site that Ancestry.com could not fullfill.