diff --git a/docs/PARTS_LABELS.md b/docs/PARTS_LABELS.md
index 54dbac5..a89a593 100644
--- a/docs/PARTS_LABELS.md
+++ b/docs/PARTS_LABELS.md
@@ -172,6 +172,41 @@ set one. Maximum length is about 430 mm.
 Copies are sent as repeated jobs rather than via the IPP `copies` attribute,
 because tape printers vary wildly in whether they honour it.
 
+**One job at a time.** The VC-500W prints at about 7.5 mm/s and accepts a
+single job at a time: anything that arrives while the tape is still moving
+comes back `server-error-busy`, which is why firing a batch at it used to
+print the first label and fail the rest. LIM now waits for the printer to
+report *idle* before each job and retries while it reports busy, so a batch
+goes through in order. The trade is that printing is synchronous — a long run
+holds the page until it finishes. **Don't refresh mid-run**, or you'll send
+the batch twice and spend the tape twice.
+
+### Combining parts onto one label
+
+Under the preview: tick two or more labels and press **Combine onto one
+label**. *Split apart* undoes it for the ticked ones, and *Back to drawers*
+throws the manual grouping away and goes back to grouping on the drawer field.
+
+Automatic grouping matches on the *drawer / location* field, which is what you
+want for a sorted drawer. Combining by hand is for everything that has nothing
+in common to match on — a custom build, a MOC bag, the odds and ends tray.
+
+A hand-made group is never broken up: it is kept whatever *Size* says, and the
+label grows 5 mm for each part past the second (two parts 20 mm, three 25 mm,
+four 30 mm). The grouping lives in the URL, so it survives printing and you
+can bookmark a set of combined labels.
+
+### Text size
+
+*Tape & layout → Text size*, 0.5× to 3×, with Normal / Large / Huge / Max
+presets and a slider.
+
+The name is sized first and everything else gives way to it: the part image
+shrinks (and is dropped entirely if that is what it takes) before the type
+does. The whole name always prints — it wraps to two lines and settles at the
+largest size that fits, so a long name stops growing before a short one does.
+Untick *Part image* for the biggest possible type.
+
 ### What to do when it won't print
 
 | Symptom | Likely cause |
@@ -181,6 +216,8 @@ because tape printers vary wildly in whether they honour it.
 | Prints sideways | Untick *Rotate for tape feed* |
 | Text clipped at the edges | Raise *Padding*, or lower *Text size* |
 | Blank or faint | Cleaning cassette (CK-1000), or the tape is in backwards |
+| *Printer stayed busy after 6 attempts* | Something else is printing to it, or a job is stuck. Power-cycle the printer |
+| Text smaller than you asked for | A long name fits at that size and no larger. Untick *Part image*, or shorten the name |
 
 ---