Halakha 2 Tawarikh 35:3: Mishneh Torah, The Chosen Temple & Sefer HaChinukh

...There was a stone in the Holy of Holies, at its west, on which the Ark was placed. And before it was the jug of manna and the staff of Aaron. And at the time that Solomon built the temple (and he knew that its end was to be destroyed), he built into it a place in which to conceal the Ark beneath in deep and twisting tunnels. And King Josiah commanded and hid it in the place that Solomon built. As it is said, "He said to the Levites, who taught all of Israel, who were holy to the Lord, 'Put the holy Ark in the house that Solomon son of David king of Israel built. It is not for you to carry it on shoulders now. Serve the Lord your God..." (II Chronicles 35:3). And they hid along with it the staff of Aaron, and the jug, and the anointing oil, and all these did not return in the second temple. And even the Urim and Tumim, which were in the second temple, they were not imbued with the holy spirit. And they no longer asked [God] questions with them, as it is said, "Until the priest would stand for the Urim and Tumim." (Ezra 2:63; Nehemiah 7:65) And they only made them in order to complete the eight garments of the high priest, so that he would not be missing garments.

It also seems that that which Maimonides, may his memory be blessed, said that it is elucidated in Joshua is from this verse, but it is not a clear elucidation at all, as we have said. And that which is stated in I Kings 8:1, “And the Kohanim brought the Ark of the Covenant of the Lord to its place, to the sanctuary, to the Holy of Holies” should also not be difficult in your eyes. It is because the Levites were not permitted to enter the Holy of Holies that only the Kohanim brought it in. And [so] the main approach seems to be like the words of Nachmanides, may his memory be blessed, that the entire tribe is fit to carry the Ark; and as it is written (II Chronicles 35:3), “And he said to the Levites, etc. ‘Place the Holy Ark in the Temple that was built by Solomon son of David, the king of Israel, there is no longer a burden on your shoulders.’” Its matter is also that Israel would have no more need to carry the Ark from one place to another; but it does not indicate that if it were to move it, that it would not be done by the Levites, and this is clear and obvious to all. And [regarding] that which the Sages said (Chullin 24a) [that] blemishes disqualify the Kohanim but years do not, it is only the priestly duties that are not affected by age, but age does disqualify the Kohanim for the labor of carrying, as it does for the Levites. (See Mishneh Torah, Laws of Vessels of the Sanctuary and Those Who Serve Therein 2.)