First, check the filter. That little Lang pump doesn't pull water through a dirty filter, and the heating system sure can't work if the water is not moving.
Take the filter out, clean it. Notice, I didn't say "rinse." Clean with a filter cleaning solution, or if the filter is over 4 years old, toss it and install a new one.
"my filter looks clean," or "I just cleaned it" - oil can clog a filter very fast, and it's usually clear so the filter looks clean.
Take the time to clean or replace the filter, before you go out and buy a new circ pump.
If the filter doesn't clear things up, then yes, look into the circ pump.
