On 06/05/2021 20:08, T i m wrote:
On Thu, 6 May 2021 18:35:48 +0100, GB
wrote:

Our 23 year old tumble dryer

Well done for keeping it that long. Many would have thrown it away
just because it was 'old'. ;-(

(!) stopped heating the air, although the
rest of it worked.

So, I dismantled it, couldn't find what was wrong, cleaned it, and put
it back together.

It's nice when it's all back and clean isn't it? When I finally
stripped ours just recently I found quite a level of fluff furring on
the insides of some of the ducts that you wouldn't normally be able to
get to *unless* you were really taking it completely to bits (things
that were held on / together / sealed with double sided tape etc).

About 6 hours altogether. It now works perfectly.

Result. ;-)

Please, please reassure me that disconnecting it from the electricity
would not have reset it without all the dismantling?

Erm ... no, *bound* to have been a bad connection on the heater
somewhere. ;-)

I agree that this is the most likely explanation, the alternative is
that it was so furred up that the overheating trip was operating all the
time.

Either way, the full strip is the way to go.