You should touch 813's components inside - I would recommend you to be familiar with real overheating right after removing a cover... I can't hold my finger on capacitors (!) between tuners' can and CPU.
Being hot to the touch is not the same as overheating.
Many CPUs are designed to run hot for extended times... so they would burn you to the touch but it is within normal operation parameters.
I'm looking at my CPU temperature right now on my iMac, for instance, and it runs for extended periods at 120 degrees F... and that's ok... but I wouldn't want to touch that with my hands.