Which observation helps to find the cause? · practice
Fixing a malfunction focuses on postbox, mailbox, existing addresses and electric door opener. Note when the problem started, which components were affected, and what changed shortly before that. Check the chain in sections and record where the operation is still present. Repeat the situation in which the error occurred after repair; a restart alone without a follow-up test provides insufficient certainty. We complete the check against a complete call with conversation and door operation from any scheduled inbound post.

