Appears that JR likes to be a little different. That is why "I" feel students need to visit the flying field before the hobby shop, then they would know what brand of radio is prefered, and what training boxs and cord setups are needed. Our field is almost exclusively Futaba, Jr radios seem to take alot of stray hits. Could be magnetism, sun spots PCBs, railroad crossing signals who knows for some reason they get hit more often.
Luckly you found the work around to the problem and hopefuly your student is progressing nicely.