More on that Steve Gadd lick from the Full Compass transcription. It’s essentially a familiar kind of four note tom ruff ending on the beat with the bass drum, with an extra snare drum note in unison with the bass. Sticking is LRLR. I’ll try to add some video to this post in the next couple of days.
Here’s how it appears in the transcription, measure 18:
The rhythm is unusual, and the best way to get it might be to play it in some more easily quantifiable rhythms, and then finesse timing to match Gadd’s rhythm— or whatever sounds good to you. The other rhythms are also perfectly valid themselves.
Line 7 is the rhythm as I transcribed it. When you’re playing it correctly, you’ll notice the snare drum is sounding the rhythm on line 6. The snare in line 5 will have the same timing, but with the ruff timed more tightly than in the finished rhythm.
Line 4 is the nearest neighbor of the finished lick; once you can play it, you can adjust the timing of the two snare drum hits to match line 6. Line 3 starts with a double left to help get the timing of the quintuplet.
The tempo on the recording is 131, so work these up to that speed at least— 131 = dotted quarter note in 12/8, quarter note in 4/4. You may find it easiest to finesse the final rhythm playing faster— the timing adjustment will be smaller.
It may help to prepare to play just the ruff, as on the bottom line, without the snare in unison with the bass.
Incidentally: you’ll notice the rhythm, with a triplet played over the last two partials of another triplet— or the last two partials of a beat of compound 8th notes— is similar to a samba “tripteenth” rhythm, which has a triplet played over the first two partials of another triplet. It’s a worthwhile area of “organic” rhythm to explore.