2010 cat 304 CCR heater fan

I've had this machine since new, and have found in winter with heat, or summer with A/C, the fan doesn't move much air... I've been working on it today and have the interior pretty much ripped out of it so I thought it would be a good time to investigate.. the fan functions on all 3 speeds and I removed the inlet filter to preclude that being an issue.. there is a very dismal amount of flow coming out the discharge end and it actually seems to blow out a bit at the filter , where in fact it should be sucking..

any input would be appreciated

Bernie

2010 cat 304 CCR heater fan