2. Question: Why does the Mishna Berura (31:2:7) allow one to take off his tefillin after kedusha of shachris on Chol Hamoed but does not allow one to take off his Rashi pair and put on his Rabbeinu Tam pair during chazaras hashatz, after kedusha, (see 34:2:14)?
A. The Mishna Berura in one place says that on Chol Hamoed tefillin should be taken off before Hallel and now people have the custom to remove them after kedusha however you have to be very careful to listen and answer to chazaras hashatz.
B. Elsewhere he says, … and not like those who take off their Rashi tefillin and put on their Rabbeinu Tam tefillin right after kedusha, and in truth besides doing it inappropriately as explained earlier in 25:13 that since Rashi tefillin are the main ones they should only be taken off by Uva litzion, also one has to listen and answer to chazaras hashatz and shouldn’t be involved in anything else.
Answer: The Dirshu Mishna Berura in footnote 3 of 31:2:7 says that since one needs intent upon putting on tefillin then one will be distracted from chazaras hashatz but when just taking off tefillin one won’t be distracted.