The 4 rail screws seem to poke into the metal plate in the base assembly. Totally n00b at this, so I’m sure it’s something I’m doing wrong. Should predrill a bit wider? Thanks
Hello and welcome to the Flow forum. A photo of the problem would really help. I built one of these a couple of years ago with no issues at all. Thank you! 
Difficult without a photo but the rails might be upside down.