Tefilla and Bechira Chofshis (free choice)

The Radomsker in Tiferes Shlomo (one of my favorite seforim) on this week's parsha asks: how can we daven 'hashiveinu avinu l'torasecha...v'hachzireinu b'tshuvah shelimah lefanech', for Hashem to bring us back to learning and cause us to do tshuvah, when these words seem to contradict the principle (kesubos 30) of 'hakol b'yedei shamayim chutz m'yiras shamayim', all is in the hands of Heaven except for fear of Heaven itself? In other words, we are given free choice, bechira chofshis, whether or not to do tshuvah, keep mitzvos, and learn Torah. If Hashem were to fulfill our prayers and cause us to learn Torah and do tshuvah, then we are merely robots and the principle of free choice is negated. So how can these tefilos ever be answered?
I imagine a rationalist would say that our tefila is not for Hashem to coerce us to tshuvah or learn, but for Hashem to place us in circumstances where it is easier for us to make the right choices. The Rambam similarly writes (hil tshuvah ch 9) that all the Torah's promises of reward in this world are just favorable circumstances which accrue from doing mitzvos and make it easier to continue down that road, but the true reward for mitzvos is only in olam haba. The Radomsker takes a slightly different approach. Chazal say that if we open a passage the size of the eye of a needle for G-d, He will open for us gateways like the doorways of the heichal. The reward we get from Hashem is completely disproportionate to the efforts we put in. While it is true that without our initial choice to learn, do tshuvah, or do mitzvos, Hashem will not coerce us to obey, but once we have made the initial choice and taken a small step in the right direction, we ask for siyata d'shemaya and an abundance of help in return. As is common in sifrei chassidus, the Radmokser finds a remez to this approach in the pasuk. The count of Bnei Yisrael was 'al pi Hashem b'yad Moshe al masa'am v'al avodasam'. The word 'al' can mean 'above and beyond' - through Moshe, Hashem responded to each person above and beyond his/her level of avodah and the burdens he/she carried.
For those willing to step outside the rationalist framework, I think there is a far simpler answer to this kashe. The Ishbitzer in Mei HaShiloach writes in Parshas Vayeira that the gemara which tells us 'hakol b'yedei shamayim' is only from our reference point in olam hazeh where we do not see how the yad Hashem controls everything. But, in truth, absolutely nothing can exist or be done in the world, including learning Torah, doing mitzvos (or more shockingly, even doing aveiros, as R' Tzadok writes many places), without Hashem being the ultimate cause. The position of the Mei HaShiloach raises many questions about bechira and hasgacha which I won't pretend I know the answer to, but given what he writes, we can perhaps understand that while in our daily lives we are blind to this level of hashgacha (otherwise we could not exist), perhaps out tefilos which soar to shamayim speak to this greater truth.