[SEDXC] Feedback Issue

[JT Croteau]

Dumb question for an Extra class op like myself but I am just in the
process of getting back on the air after being mostly off the air for
the past 12 years so some things are a bit rusty.

Anyway...

I just installed a Butternut HF2V vertical for use with my Ten-Tec
Paragon.  During inital adjustment of the antenna, my MFJ-259B is
showing the following on my ideal 40M center frequency (currently
optimized for working 3Y0X on phone):

7.200 - SWR 1.4:1
R = 37   X = 13

Now, when I transmit on 40M I am getting some kind of feedback as I
also hear myself in the speaker on the Paragon.  However, when I
operate into a dummy load there is no feedback.  I also do not have
this problem on 75M.

Am I correct in thinking that I have some type of RF grouding issue? 
Should I add a RF choke in the feedline or look at some other problem
first?

Thanks

73
JT, W6FO - the newbie Extra who should probably be demoted to Novice