Mamiya 645e meter

[claystork]

Just got a 645e on ebay, it seems to work fine in all aspects other than when I change the film speed and look through the meter finder, there seems to be no change in exposure from say iso 160 to 400 etc. It seems to be reading everything as if it were set at roughly 160. You would think if you were metering and switched the dial from 160 to 400 or 800 youd see a jump, right?