After 17 years service my TS430s also exhibited the problem of low RX over frequency ranges which coincided with the ranges of the LPF's on the filter unit.
Fix:
Remove filter board, and remove plastic covers of the relays by gently prizing with a small sharp-edged screwdriver.
Cut a narrow strip of photo-copy paper, insert it between the contacts, and apply pressure to the contacts as you withdraw the paper. Paper is relatively abrasive, and this will clean the contacts.
I found that that some of the contacts hardly made contact before the relay armature was fully home. Fixed by bending the contact finger so that the contacts made before the armature was home - this ensures adequate contact pressure.
Fix:
Remove filter board, and remove plastic covers of the relays by gently prizing with a small sharp-edged screwdriver.
Cut a narrow strip of photo-copy paper, insert it between the contacts, and apply pressure to the contacts as you withdraw the paper. Paper is relatively abrasive, and this will clean the contacts.
I found that that some of the contacts hardly made contact before the relay armature was fully home. Fixed by bending the contact finger so that the contacts made before the armature was home - this ensures adequate contact pressure.