Toro 20334 hard start on electric start, easy on rooe

Working on this 20334 Toro mower, it has a 7hp Briggs. I’ve replaced the battery, air filter, plug, oil, and removed and cleaned the carb. It starts like it should on rope, but it cranks and cranks on the electric starter. It does eventually start, but it takes a lot. I’m not sure if the starter isn’t cranking fast enough or what.

The mower belongs to my elderly neighbor and she needs her electric start. I saw one video where someone started a Toro on battery and it fired right up. Any suggestions?