Can someone recommend replacement tubes for my MFA MAGUS A2 Preamplifier please?

Thank you JPerry. I did reach out to the Tube Depot who were very patient and helpful. I ordered 2 of the Tungsol 12AX7 as a start and I’ll see how they help. 

TonyKay and Elliot, 

I replaced the tube that in my MAGUS is the one that after reading the manual and receiving advice from the very gracious Scott Frankland the problem persists. To ship the unit to Scott and have him repair it would cost as much as $800. total and that creates the question of wether it is worth the cost to repair? I just do not have the requisite expertise to answer that question and hence I am hesitant on spending what will be over 50% more of my original budget for a tube preamp, the MFA MAGUS, the MIETNER monoblocks and the BOZAK URBAN speakers all for $1,450.. should I buy another used tube preamp or a new one such as the Schiit Preya+ or do the repair? 

I actually found a highly recommended local tech through a local audio shop that I happened to see the owners being interviewed on YouTube. Thank you for your comment.