My friends' gas Roper Charm actually was in a house they rented. The landlords were rather unsympathetic, and as long as one of the two ovens worked, they weren't about to replace the range. They finally had to move to get away from that range (to a house with a 1980s Caloric range--some upgrade...). The last few years they lived with the Charm, they only used the upper oven, as my friend's dad had rewelded the lower oven's NLA burner as many times as he could. As Tom said, the parts went NLA an amazingly long time ago--this would have been in the early 1980s when they first looked for a new burner. I imagine that back in the day, the Roper Charm was the budget alternative to a Flair (and came in gas, too). But as the test of time often proves, one gets what one pays for.
T.
P.S. You can imagine how out-of-luck you were if you had to take something out of the lower oven on the 2-oven models when the cooktop was rolled out. Such a thoughtful design.