dheadley -- Welcome into the company of true veterans (and descendants) of the 390th Bomb Group, most likely as a member of the 570th Squadron.. Take a look at the Research section at www.390th.org
-- you will find your grandfather's name if you look at the 'Personnel List' and 'By Crew Member Name' areas.
Your grandfather flew 35 missions from June 2, 1944 to September 27 1944. In the 'By Crew Member Name' area, here is the link
(although you could do this yourself easily enough). Their format requires single quotes. Just in case spelling or format of last name-first name is not exact, I would suggest using their wild card (%) symbol. When you research in direct fashion, you would want to enter 'Wickiser%' and results will be for all people with such a last name (only one in your case). Your grandfather flew exclusively with crew 90 after his first seven missions. Philip S. Horton produces about the identical profile. Take note that the link also lists airplane numbers -- you can research the fate of those specific airplanes in the research 'Mission Summary' area. As I did you will probably spend hours researching the other crew members and cross referencing flights, etc. (remember to search on 'lastname%' and don't bother with first names until you get things nailed down).
I have my father's copy of the 1947 'Blue Book', The Story of the 390th Bombardment Group (H)
-- many unit histories were offered after WWII to members of those units. I recall sitting in airbase libraries as a kid and reading wide-eyed about air, naval, marine and army units throughout the world. The index of personnel in the back of the Blue Book is not perfect and I do not see your grandfather's name anywhere (they even have a small section at the end titled 'Not listed in unit rosters' that has produced results for some relatives asking questions). I'd say your grandfather's history is quite intact due to the fact that the 390th BG museum in Tucson (and website) has him listed.
Hugh 'Skyguy5' suggested contacting Carolyn or Jean. That could help -- please let us know how much more you learn from them versus off the 390th website.