thompson DTI 6021 will not record?

Set programs to record. recording failed message shows that recorder missed the program showing code hash 0402.
Also the recorder intermittently shows the the no signal symbol. We do have other devices connected in sequence such as talk talk box and Video recorder, this has worked up to now strange? the tv setup has not been changed cables all intact.
Any ideas please before we replace the recorder

michael
January 2015