A few days ago I posted about the Line 6 M5 Stompbox modeler. On Facebook, there was one mention of how the footswitches were really not that great. Basically spring switches making direct contact to switch pad on the circuit board. Seems like problems could crop up with this, and could be an explanation as to why my Line 6 DL4 has been acting up.
After that comment, another user mentioned that he swapped out his footswitches and his pedals are working fine now. He provided a great link to a video where Juffage breaks down a Line 6 DL4 and shows step by step how to replace these spring switches with momentary switches. This would apply to other Line 6 boxes like the M5… but please… proceed at your own risk.. and know your limitations and capabilities before attempting.