Defrost cycle questions for refrigerator

I have a Frigidaire, top freezer, 1998 model, that lost cold in the bottom and frosted the back wall of the freezer.
Hoping the defrost timer was guilty, I bought and changed the timer (I know, don't just change parts without diagnosis). Hair dryered (is this a word?) the heavy ice out of the freezer to get to the coil thermostat and heater. I pulled out the thermostat - it had good continuity when cold, and broke continuity when it got hot (over a space heater). The Fluke digital ohm meter buzzed continuity and read 27 ohms on the heating element. I do not know what ohms it should read.
I reassembled without installing the back plate or ice maker and ran it long enough to get everything cold, all fans working fine. I advanced the timer to defrost and re-checked the coil thermostat which still showed good.
Should the heater get hot to the touch? It got warm at best, and that required imagination. Defrost time lasted about 15 minutes. I don't want to put this thing back together if it is not right. I don't want to just keep changing parts though I am well ahead of buying a new unit and the work is simple while the unit is empty. We have a back room refrigerator so we are not desperate, but wife is saying she'll just go buy a new unit.
I let the unit run last night. How frost free should the coil be? I have a healthy layer on the coils.
I would appreciate the advice of a technician or someone who really knows.
______________________________ Keep the whole world singing . . . . DanG (remove the sevens) snipped-for-privacy@7cox.net
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