the 500 watt H-channel amp has a push assembly. 2 fans total (see below)
service_manual - service manual can be found here.
blah500_fans - 2 fans total,
2 in back (push).
24Vdc/0.21A; 80x25mm; 3 wire lock rotor; 45.9 CFM; 3110KL-05W-B79 originally. Replacement: 3110KL-05W-B69-D00 (B69 is 41CFM but can't find others in stock) from Newark or Digikey ($10/each)
Power Supply Fan -
the internal power supply module needs 1 fan below:
? originally. Replacement: ?
BLAH500
BLAH500
BLAH500
BLAH500
BLAH500
Power supply
BLAH500
BLAH500
BLAH500
BLAH500
BLAH500