The band actually had two successful stretches -- a funk period from 1973 to 1975 or so best illustrated by "Jungle Boogie," which hit #4 in 1973, and a smooth R&B period from 1979 through the mid 1980's. The R&B sound was helped by the new leader singer James "J.T." Taylor, who joined the band in 1979 (and parted amicably in 1988 to focus on his solo career).
"Get Down On It" was a solid hit for the band, and peaked at #10. It was the 5th of 15 top 40 hits that the band would have between 1979 and 1986. They also had 4 top 40 hits during their earlier funk period, with a multi-year dry spell in between. While the song was a hit, the video remains rare, partly due to the blurred images and partly due to the fact that early MTV was not friendly to R&B acts -- hence, its inclusion on ERV.
While there have been some personnel changes, Kool & the Gang remain active in the music industry to this day.