Bendix 6106 burn-in behavior

I've read that the Bendix 6106 can be a very good rectifier tube, but that it takes a couple hundred hours to burn in. And that during that time it can misbehave.
I've been burning in an NOS JAN Bendix 6106 for about 50 hours or so. Today I notice a slight hum on my phono channel, and the volume on the left phono channel is way down. However, on other sources, both channels are hum-free and have appropriate volume matching.
Do I have a bum tube? Or is this a normal behavior during 6106 burn-in? Preamp is Supratek Cortese with LCR phono stage. The seller has said he's willing to swap tubes to ensure my satisfaction...
Thanks, in advance, to anyone who has some experience to share.
This issue of "burning-in" a rectifier tube is NONSENSE! It either works right away - or it doesn't! I speak from experience as a longtime tube user! As long as a rectifier tube is operated within its current/voltage rating, all is good! Different rectifiers drop the B+ voltage by different amounts. This affects overall circuit parameters. A rectifier tube has no "sound" per se! Expecting it to sound "better" after hundreds of hours is lunacy!
@markusthenaimnut- If the tube is being used in the preamp, any abnormalities will be noticed on all sources. If your preamp has a tubed phono stage, swap that stage’s tubes, to see if they’re causing the problem. If not: reverse the interconnects from the arm/cart, to the phono stage and the imbalance should follow.
Thanks to both of you for your responses. Here's a little more information - 
The builder of my preamp has advised that the tube is faulty. Replacing the Bendix 6106 with the stock tube immediately eliminated the problem, and the seller has issued a complete refund.
Regarding the topic of burn-in, the tube originally functioned with no problems. I claim no expertise with respect to burn-in of this tube; quite the opposite. I had read on this forum another individual's experience with this type of tube in an earlier version of my preamp. I based my expectation on the need for burn-in on his comments.
However, the phono stage in this latest design is extremely resolving and that might mean that this tube is no longer a good match for the preamp. From here on out I plan to stay with the stock tubes.
Hi Mark, Does Mick of Supratek endorse the Bendix 6106? I was under the impression that he does not. Can someone correct me if I'm wrong?
Thanks, Tish

Hi, I did a search and it looks like they are good to go (the 6106) although I did see a post that claimed you shouldn't use it in a Cabernet.
Thanks again, TISH
@roberjerman is correct- unless the idea of 'burn-in' is extended to the idea that some percentage of parts will suffer 'infant crib death' due to manufacturing defects, as is apparently so in this particular case.

Glad you got it resolved. Of course, being the highest-gain, and earliest, circuit of a preamp, a phono stage would be the most(noticeably) affected, by a misbehaving rectifier. How basic! I was hoping; getting old would take longer!
In my correspondence with Nick he did not directly advise me or suggest that the 6106 was incompatible with the Cortese. But I do recall reading a post somewhere to that effect. But he doesn't call it out on his substitution list, so maybe that should have given me a clue. 
So Mick did not give you a straight answer on whether or not 6106 is a go, that doesn't help. So all you know is that you had a problem because the tube you tried was bad. Mick is on vacation right now, don't know if he is answering emails or not until he returns. It would be really good to know as I planned on using the 6106 in the Pinot Phono stage that I ordered. I did use the Bendix 6106 in my Syrah Pre Amp with no problems. 
Correct - not a direct answer. But I will be following up with him on this and other similar questions.

BTW, don't underestimate the stock tube configuration. I think I personally had become somewhat infatuated with the idea of rolling tubes, and a subsequent experience has me wondering if what I heard was due to the way I had my cables dressed, because I experienced hum again, then remembered the cautions documented in the owners manual about the sensitivity of the preamp to nearby external sources of electrical fields. Re-dressing my cables eliminated that hum.