Instrumentation amplifier output stuck high
From the datasheet, the maximum output swing with a +/-15V supply for the TL074 is about +/-12V.  The common mode input range for that power arrangement is -12 to 15V. 

While they don't supply the numbers for 0V and 5V rails, it's a fairly safe bet that, without a negative supply, the input range does not include ground, plus you don't have much headroom on the output.

All in all, the TL074 is a poor choice for a 5V single supply.  You should look for an op amp that is rail to rail on the inputs.  For TI, I believe you should look for a part that begins with TLV, but please verify (those won't be the only rail to rail parts, and I can't guarantee that every TLV part is rail to rail).  The part may or may not be pin-compatible with the TL074, but the pin layout of the TLV074 is very common.

There is also the possibility that with a gain of 250, you might simply be saturating something because of a simple offset somewhere.