I just bought some 18c's exclusively for the battery door for my 28s's broken one.

[edryer]

My advice borne of long experience with various 28S "fixes".

Never use the recommended batteries, heavy stress on the door and the device however you try to fix the problem.

Get some dowel, and tin foil, cut one to a size slightly shorter than two watch cells, and the other slightly longer, cover with the foil (you get the picture) use the two watch cells at the top of one of the dowel pieces... this works PERFECTLY with no door stress, I mean ZERO.

Actually I didn't even use dowel as I "moulded" the spacing with just tin foil in the shape of batteries.

Also the watch cells seem to last ages, as long as the usual batteries, don't ask me why.

Not my idea... saw it on the net, works fantastically.

PS. I use this on my 28S and it eliminates all issues, but you always have to be careful when removing/placing the battery door anyway with the 28S (brittle due to age), even under normal circumstances!

The other common 28S issue with the heat stakes... I think Geoff Quickfall investigated and fixed this - not at all easy for mere mortals like me ))
Ok that is here: https://www.hpmuseum.org/cgi-sys/cgiwrap...ead=185173

How I love my 28S, the best HP ever made... pity about the issues but with care you can still use these devices day to day.