Hello. The mains filter would never only trip the electrics 5 mins into the drying cycle. If it only trips on the drying cycle it must be something that is only in play during the drying cycle and not the wash cycle.
The main suspect has to be the heating element but It could be something else, especially as it takes 5 mins or so. Unfortunately though, unless you can see anything obvious you need an insulation test meter to diagnose this type of fault. Without one you are unable to see what is causing it to trip as described here washing machine tripping electrics