The crystals you are trying to measure are probably 3rd overtone crystals, and
you are measuring the fundamental frequency. If you just run them in an
oscillator with no series tuned circuit at the frequency of interest then they
will oscillate at the fundamental frequency.

Try a series tuned circuit in series with the crystal, tuned to the 35Mhz
frequency you are interested in. It will not need to be a high Q circuit, but
will need to have reasonable rejection at the 11Mhz and also at 55Mhz (the 5th
overtone frequency). Getting it tuned exactly is not a problem.

To make sure it is in the right ball park, short out the crystal socket, and let
the oscillator free run with just the tuned circuit. You should now be able to
tune it to produce an output frequency close to the required crystal frequency.

You will only need to do this once before testing the first crystal, from then
on you should be able to plug in crystals, and have them operate at the correct
frequency.