You need to check firstly if WECCL is part-of-speech tagged, if not, you may tag it using TreeTagger or CLAWS (with different tagsets). Write a regex for your query, tick the regex funtionality in AntConc.
Apparently it depends on your research question(s). This is probably a spelling mistake, and the students intended to say so, hence the wrong forms may be included in your statistics. You may like to refer to the error-tagged CLEC.