[Boatanchors] Bird 43 Problem

[Bill Pancake]

Any ideas why my Bird 43 wattmeter will read correctly in the "forward power" slug position but NOT in the "reflected power" position? 

The slug (element - 100H) is working perfectly and meter works perfectly. Does it have something to do with maintenance of the thruline section? Have tried two different (one new - one used) 100H slugs - same problem, no reflected power reading. 

Another wattmeter (Drake W-4) shows reflected power in my test setup. Any suggestions appreciated. Tnx, Bill, wd0x