The Socoh Excavation, led by Yuval Goren (known most prominently as a clay analyst), has opened a website right here. The website symbol is the S4L lmlk impression. The website suggests it was Socoh-Khirbet ‘Abbad that was the lmlk pottery (my previous guesses were Lachish and Achzib-Tell el-Beidah). Also, only one Socoh lmlk impression (out of over 14 lmlk impressions found at the site) was found at the Tel. Curiously, while the website emblem is an S4L (L for ‘Lapidarist’), the lmlk handle found at the site appears to be an S2U (U for ‘Undivided Bottom Inscription’).
The website’s reasoning behind Socoh being the lmlk pottery appears to be faulty. Socoh was the last geographical name to have its own lmlk impressions (there are no “S4C’s”) and a lone Socoh impression at a major Shephelah city is nothing unusual. If Elah Socoh was lmlk Socoh, we would expect Socoh to be the first GN to have its own lmlk impressions and not just one, but at least seven Socoh lmlk stamp impressions to have been found in the survey of Elah Socoh. I would suggest, if Yuval Goren is right, the lmlk pottery was most likely located at Achzib/Tell el-Beidah. I have always thought the lmlk Socoh to be Shuweika E. of Dahriya since I began doing serious research on the subject of lmlk impressions.