At the bottom of the daf (b), the Gemarah suggests that you learn the owner of the Korban (Sotah) does 'Hanafa' from Shlamim, and then you apply that to Nazir as well. Is there not a rule about something learned from a 'gzerah shava' not being able to be applied elsewhere via another 'gzera shava', particularly in Kodshim?
Yonatan M., Toronto, Canada
I think that you have in mind the Sugya in Zevachim 49b which states that something that is learnt from a Hekesh cannot teach further with a hekesh. Rabbi Yochanan also states there that in the entire Torah something which is learnt out can also teach in return, with the exception of Kodshim.
However the Gemara there 50a also asks whether something which is learnt from a Gezera Shava can in return teach others with a Gezera Shava. The conclusion of the Gemara there (top 50b) is that such a Gezera Shava can indeed be applied elsewhere (and the gemera there is clearly discussing Kodshim.)
See Gilyon Hashas there 50a who cites Tosfos Zevachim 44a DH v'Asi who points out another Gemara that learns that a gezera shava can re-teach, and writes that the Gemara 50a could have in fact cited the case mentioned by Tosfos 44a.
Now we can add on another Gemara - our Gemara kidushin 36b - that a gezera shava can be Chozer u'Melmed b'gezera shava. So the answer to your question is that gezera shava is an exception to the rule that in Kodshim the Lamed cannot go back again to Melamed.
Kol Tuv
Dovid Bloom