VPI HW-17 - brush too short?

I am relatively new to vinyl but had collected a sizable number of records in a short period of time. In order to better dedicate my time to music instead of record cleaning, I bought a used VPI HW-17 here at A'gon. However, I found that the accompanied brush is probably just about 4 inches - the "effective length" is even shorter when the brush holder is clipped slant into place during operaion. Therefore, aside from LP of really short grooves a large percentage of surface cannot not brushed up - still need to manually clean the inner grooves, totally defeating the purpose of getting a RCM. Tried to find info on replacement brushes online, but no word on if they come in difference sizes??