[Harp-L] CR41 feedback situation

[Milehighdrums@xxxxxxx]

Hi,
I've been surfing around this harp l archive for a couple of months, ... 
waauw  ... what a wealth of information at the click of a button... .   A big 
thumbs up for the people who are involved with keeping this wonderfull site up and 
running :)

I recently bought a shure green bullet CR41 with 99H86 controlled reluctance 
elment(R7???) ...  some pro's seem to call this one the Holy Grail...
  I get feedback at volume 2 1/2, ...  my other green bullet. 520D with CM 
made in Mexico,... no feedback until 5  ?!?  
My amp is a fender reissue blues junior (12" Jensen speaker) with a 
12AU/12AT/12AX tube line up.

How can I crank up the volume of the CR41 without the feedback nightmare ???
More 12Au's ?? pre amp??? or alternate CR41??? 
A big thanks in advance for helping me out...
Harp on !!!!
Kurt.