| Case | Ruling | Reason |
|---|---|---|
| May one restore the lower hinge? (צִיר הַתַּחְתּוֹן) | Tanna Kamma: Mikdash: permitted · medinah: forbidden | — |
| Rabbi Yehuda: Permitted even in the medinah | — | |
| May one restore the upper hinge? (הָעֶלְיוֹן) | Tanna Kamma: Forbidden in both places | — |
| Rabbi Yehuda: Permitted in the Mikdash | — |
The whole case turns on a detail easy to miss: the door is the door of a chest — a keli — not a room. That is why it is even a question. The Tosafos Yom Tov sharpens it: the entire machlokes rides on whether the melachah of boneh (building) applies to vessels at all.
Tanna Kamma: reset the lower hinge in the Mikdash — the upper one still holds the door, so it is an easy fix, not real boneh. The upper hinge is forbidden everywhere (kan v'kan asur): without it the door drops, so reseating it is boneh, or you would hammer it home — makeh b'patish, the finishing blow that completes a vessel. R' Yehuda goes a step further (upper in the Mikdash, lower anywhere) on the principle ein boneh b'keilim — no building applies to vessels — so the act is rabbinic at most, and ein shvus baMikdash; with the kohanim mezarzim, scrupulously careful, no decree is imposed there.
A tzir was a pin turning in a socket bored top and bottom; the door pivoted on it. The lower pin sat under the door's weight and could be eased back once the upper one held; the upper pin, bearing the leaf, was the hard one to reseat — which is exactly the line the mishnah draws.
This belongs to the series’ closing set on a single principle — ein shvus b’Mikdash: the rabbinic Shabbos restrictions (shvus) that bind everywhere yield inside the Beis HaMikdash. The reason the series draws out is trust — the Kohanim, serving before the Sanhedrin, are assumed zealous enough not to slip into a biblical violation. This mishnah sets the principle in place; the ones beside it press on how far it reaches.