[hypoxia]

After rereading the OP post, I realized the question is about the elbow fitting which should be a 1/4" Male NPT to 1/4" tubing like this Push Fitting .  Those fittings are easy to replace but will eventually leak again.  Many Gurus will replace the fitting with a compression fitting like this Compression elbow .  I go a slightly different direction and install a Street Elbow like this Street Elbow and a straight compression fitting like this 1/4" Compression Fitting .  Most hardware stores have 1/4" Brass Elbow and 1/4" Brass Sleeve which will also do the job.