Butternut HF6V antenna 40m trouble

 The table above shows the SWR before and after on My HF6V vertical antenna. I recently noticed this antenna would not auto tune on 40m , so I did a more in depth antenna check and realized i had lost good SWR on 80,40 and 30m. The upper bands - 20,15 and 10 tuned OK so the problem was not an open coax feed but more than likely a Capacitor,connection issue.

I read through the manual and realized the 80/40m capacitor assembly was maybe the problem area. I hope the door knob capacitors were Okay since they seem to be a rather pricy item to replace. I began by close examination of the connections, capacitors and related hardware. I did not see any particular issue so I took apart each connection one at a time . I used a anti-oxident compound on each connection I reassembled to prevent corrosion. 

 I periodically rechecked SWR before continuing on with too many connections but had not found any specific problem. Eventually I disassembled the door knob capacitors and found a large amount of oxidation on the screw threads where the capacitor and bracket connected. I cleaned this connection and put back together and tested for SWR. It now tested very good on 30 and 40m and even 80m tested good although for a limited bandwidth--exactly like the specifications show!

  This antenna works for now but I will need to check more connections before too long!

73---Tim