How do I repair unravelled seam on Retro-X jacket?

Hi, the sleeve seam on my Retro-X jacket unravelled from armpit to elbow. It's a tricky spot - the seam is serged and I'm not sure how to best repair it without a serger without it looking terrible. Advice welcome as the jacket is otherwise in great condition.

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0

crwdns2942205:01crwdne2942205:0:

Tried local dry cleaners that may specialize in clothing repairs and specifying serge sewing?

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

crwdns2934285:0crwdne2934285:0