my previous dojo has A LOT of yudanshas so they take turns on taking charge of the new people. and the Sensei didn't bother with the new people too much, because most of the people that came there were really prepared to train and learn hard. so they actually listen and remembers what were shown in the front(just 4 times for each technique, 1 left and right omote, 1 left and right ura). we were basically taking care of ourselves most of the time.
That's what your sensei should do. He should get the seniors to take turns teaching the newbies. While a senior is teaching newbies, the other seniors can get the training they need. That's what my dojo does. Talk nicely to your sensei about your problem and suggest that the seniors take turns teaching the newbies so that all the seniors get the training that they need. A newbie must pair up with a senior so that the senior can guide them. When I was a newbie and I paired up with another newbie, we were both clueless and didn't know what to do. We were all newbies once, we all needed seniors to teach and guide us otherwise we'd be so lost. If my seniors were unhappy and impatient when teaching me, I wouldn't be happy either. I might have even lost interest and been scared off.