I've never worked with WE mags but I imagine all GBB mags are built generally the same way. So if I understand the problem correctly, you're having trouble getting the baseplate pins back in. What you have to do is make sure to put alot of pressure on the plate while you're trying to knock the pins in, otherwise the holes don't line up correctly. Your thumb won't do it. Try bracing it against the edge of the table and put your body weight behind it, then gently tap the pins in. Hope that helps.