ParkerSal, I ordered from Fore & AFT Marine .They have all the wiper parts for our Parkers. For my 2120 the part # VT-RWBS. Located in FL.Tel# 727-391-0730.
I took the whole damned blade assembly to my local Autozone and replaced the whole stinking blade with a proper car wiper blade that fits the boat wiper arm properly. Now, when my blades need changing, I can replace them instantly for a couple bucks each.
On the cheap side I took the arm to WMT and got replacement inserts. They are way too long so just cut them down w/ a dremmel. 2 inserts for ~ $3. Been doing it for ~ 4 replacements ~ 1+yrs out of each.