I have the exact model, But i did not experience that which you say,
my injector is about 4 yeas old now, but still it is made here in I
believe NY, so yours needs to be replaced, what you say is not
normal for any wax injector. call the company again, they are very
customer friendly even though they may not take care of the actual
return, but direct you back to the retailer you purchased from. mine
was quite clean in terms of metal and other parts. I personally
exchanged the hand pump with a German bike foot pump it works great,
hands free and air pressure when you need it however much, no
compressor noise,no energy for a compressor,no extra cost for the
pressured air. and you get a little exercise while pulling waxes.
deffinatly look into returning ASAP do not bother cleaning it any
longer and wasting your time. if they offered a new one deffinatly do
it, you might have gotten a funky one.