Here is an reducible force strut that can handle up to 90 lbs.

http://www.mcmaster.com/

6465K12 Reducible-Force Gas Spring 3.94" Stroke, 90 lbs Max Force, M5 Male Thread Sz
1 x $31.36 = $31.36

6465K25 Nylon Eyelet End Fitting for .59" Cylinder Dia Reducible-Force Gas Spring
2 x $1.20 Each = $2.40

These do not appear in the their catalog, but they do sell it.

The two original bushings won't fit inside the new eyelets so use two 1/4" flat washers instead.

The new strut comes overcharged so you have to let some of the nitrogen out to adjust the force by backing out a tiny hex screw. You have to be careful or you can release too much pressure ... the strut is worthless.



Just in case these are not available here are some measurements of the original strut with digital calipers
Strut

A = ( B + C ) = ( 5.708 + 4.224 ) == 9.932 inches
Total length of strut (base of eyelet to base of eyelet)

B = 5.708 inches
Length of gas strut (base of eyelet to end of gas cylinder)

C = 4.224 inches
Length of shaft (base of eyelet to base of gas cylinder)

D = 0.239 inches
Width of shaft

E = 0.600 inches
Width of gas cylinder

Eyelet

F = 0.430 inches
Length of eyelet from top of eyelet to center of eyelet (approximation of center)

G = 0.610 inches
Length of eyelet from base of eyelet to center of eyelet (approximation of center)

H = 0.326 inches
Width of eyelet