AP Checks - MICR font recommendation

Hello all,

We have just upgraded from EBS 11.5.10.2 to 12.1.3. As part of the upgrade we are now printing checks using BI publisher. We have been able to work out most of issues, but are stuck on the quality of MICR line. We are using Micr MT font provided as part of BI Publisher desktop. Our bank, Wells Fargo, is rejecting the width/density of the font. We are using HP 600 M603 printer, using maximum possible density of 5. 

I tried Gnu MICR as well - which looks almost identical to Micr MT. I didn't notice any difference in width/thickness. 

Should we purchase a commercial font? If so, has anyone had any experience with Wells Fargo? Can you recommend a particular font that is not very expensive and yields good results? What kind of license should we purchase if we buy the font? Is single user ok?