Chespirito fans in Brazil have been hunting down two pieces of background music that were used in promos and, famously, as intro music for the Brazilian dub of El Chapulín Colorado. The existing excerpts of these tracks are the following:
This track was used during the intros of Chapulín episodes dubbed in 1984. It's unknown whether the intro (which ends at the :15 mark) is part of this piece or not.
This one was first used in El Chavo del Ocho promos in 1989, being adopted as the standalone intro song for El Chapulín Colorado in 1993. According to a YouTuber, it may be a version of a traditional "Clarinet Polka" (the video includes an excerpt of this, for comparison purposes), but even with this intel we haven't been able to locate the exact recording/version of this track.
If you are familiar with this kind of music and wanna help identifying and finding clean recordings of these tracks, you efforts are very welcome!