Hi Gregg, how many BTUs is that right front burner on your mom‘s stove, it should be around 12,000 BTUs a look at the nameplate of the range will tell you.
The most likely problem is the orifice or orifices are slightly clogged. this can happen on any Surface burner on a gas stove. We have to clean them out all the time when people complain about lower than the usual flame sizes.
The ironic thing is with stoves like this. I’ve had quite a few customers over the years saying the fire is too big and they don’t like the way it Flares out beyond the pan they feel like it’s dangerous so we derate the burners we take one of the propane orifices that are packed in a little thing on the back of the range install that and drill it out to a lower BTU usually cut it down to about 10,000 so the flame is not so large