So I found a 400. Haven't looked up the year yet. Runs but has carb issues. Here's the problem... when I looked at the tractor I didn't notice the gauge on the dash was an oil pressure gauge, I guess I just figured it to be an amp meter. So I but the tractor and haul it to the shop, looking at the glory of a big 400 and wondering how I'm going to explain it to my woman, when I noticed. The tractor is sitting there running and showing 0psi. So, is this supposed to be an oil pressure gauge? Maybe not and it's not hooked up? Where should I start?