please download v.1.7 build documentation for details.

Service advisory: after building the snare you must place a jumper as shown in the pic below, this is shown without parts placed for clarify

bigger picture from me - easier to find the place..

change the 5.6V zener as shown here:

from FB RE-909 group:

"Hello! Just wanted to share some good news about noise and crosstalk issues on RE-909. Pictured below is a Roland TR-909 factory mod with a wire that seems to reinforce grounding between C151 styrofoam cap in the hihat low pass filter and the common analog ground track where R236 is also attached. By doing the same mod in RE-909, pictured below also in the bottom of the board, cymbals crosstalk and digital noise leak into the hihats channel is eliminated, which fixes the last remaining issue in my build. I used a thick grounding wire to connect the lower pin of C151 to the double hole in the common ground track next to R236. This fix works perfectly on traffo PSU but I can’t guarantee it works on safe PSU (and preliminary tests show it doesn’t) because of the difference in ground routing. Otherwise, enjoy your digital noise-free, crosstalk-free RE-909!"

there's a failure in MIDI section

rev2_service_advisory_jan23.pdf

only for rev.1 pcbs:

as described in the rev.2 guide, is there a extra trimmer for  the noise,

for rev.1 pcbs you should be able to cut a trace between 2 resistors and install a trimmer 

only needed in rev.1 (rev2 still has this fix) 

use few millimeters height paper to get a correct alignment:

https://note.com/re_303/n/nd37b0d0ab809