The TS-440 FM receiver seems to be constructed for 25kHz steps. Using 10kHz steps, the bandwidth is much too wide.
Using the 8.83 MHz filter on the RF board, which is normally bypassed by FM solved this problem and I got a very useful FM rig, even with the original F-Type filter.
Required parts: 2 diodes 1N4148
Disconnect the power supply and antenna from the transceiver.
Using a #2 Philips screw driver, remove the screws from the bottom cover. Remove the bottom cover from the transceiver.
Locate resistor R59 and capacitor C131 on the component side of the RF board.
Using a #1 Philips screwdriver, remove the screws that secure the RF unit to the chassis of the transceiver.
Remove all plugs still keeping the board in position.
Pull the board up and rotate it towards the front of the transceiver to expose the foil side of the board.
Find the junction of R59 and C131 opposite their ground connection.
Disconnect R59 from C131 by scratching the track with a sharp knife.
Install and solder diode A with anode connected to R59 and cathode connected to C131.
Install and solder diode B with anode connected to R58/C131 and cathode connected to C131.
Remove resistor R57.
Reassemble the transceiver by reversing the steps 1 to 6.