Larry Mayo writes asking about upright damper spring strength.
There are technicians who can give you exact gram specifications.
My advise is more rule of thumb.  If it works it is probably right.

If the damper springs are too strong the damper lift rod will bend
when you step on the sustain pedal.  This is especially true in some
of the less well-designed (cheaper) pianos with thinner lift rods.
If the springs are too weak the dampers will not damp.

I find flat damper heads take more strength than wedge style heads.
Larger and longer strings take more strength than short strings.
Damper head placement and felt composition is more critical than
damper size; however, larger damper heads usually -- but not always --
work better.

If no one has been at the dampers before me I try to match the old
dampers as best I can.  The last time I ordered (about a year ago)
American Piano Supply had the widest selection of damper heads.

Tip:  If you buy the treble damper heads with the wood blocks attached,
buy them in a strip.  Number them and then cut them apart in groups of
four.  Cut these groups into groups of two, then cut them into single
dampers.  This way the sides stay straight.  If you just cut them off
one at a time the felt pulls more from one side and you end up with
parallelograms on wood blocks.

I use a new razor knife with the type of blade that you can break off
sections when they get dull.  Extend the blade the full length and you
can cut down between the blocks and through the felt.

John Dewey