diff --git a/rust/pm-kit/src/main.rs b/rust/pm-kit/src/main.rs
index 9091b73..ee9cae0 100644
--- a/rust/pm-kit/src/main.rs
+++ b/rust/pm-kit/src/main.rs
@@ -266,23 +266,12 @@ fn main() -> ! {
         // ---- draw: on change, and periodically (so a draw lost right after init reappears, and
         // the playhead advances). ~7 fps; partial/playhead-only redraw is the next optimization. ----
         if full_redraw || now.wrapping_sub(last_draw_us) > 140_000 {
-            let lanes: Vec<pm_ui::LaneView> = track
-                .lanes
-                .iter()
-                .map(|l| pm_ui::LaneView {
-                    name: &l.sound,
-                    levels: &l.levels,
-                    beats: l.groups.iter().map(|&g| g as u32).sum::<u32>().min(255) as u8,
-                    poly: l.poly,
-                    muted: l.mute,
-                })
-                .collect();
-            let screen = pm_ui::Screen { name: NAMES[idx], bpm: tempo, playing, phase, lanes: &lanes };
-            if notation {
-                pm_ui::draw_notation(&mut display, &screen).ok();
-            } else {
-                pm_ui::draw_metronome(&mut display, &screen).ok();
-            }
+            // DIAGNOSTIC: draw the confirmed-working bring-up pattern instead of the metronome,
+            // to isolate whether the blank screen is draw_metronome or the heap/display path.
+            // If you see blue + 4 colored corners + "TL"/"PMK" → display+heap are fine and the
+            // bug is in draw_metronome. If still black → it's the heap/display, not the drawing.
+            let _ = (notation, idx, tempo, phase, &track); // keep state alive while diagnosing
+            pm_ui::draw_ui(&mut display).ok();
             full_redraw = false;
             last_draw_us = now;
         }