Welcome to the LEC,
Hand on heart I haven't heard of that many steering racks giving up the ghost, but I've heard of a few power steering pumps, (much more likely)
A know fact of hard steering is a partially collaspsed steering column, (Has the car been in an accident?)
I believe the Rack & Pinion for the Fed SIR are still available at the aftersales price of £212.75 + tax, normal price £1,051.80 + tax

. (I bought a fed rack several months ago,but I am UK based, god only knows what the postage would be) on a positive note it comes with the impossible to obtain track rod ends.
Repair could be an oppotion, Lotus do a seal repair kit, but I don't know if it comes with the aluminum retaining ring that corrodes badley.
Have a glance at this thread and it may give you some insight into your rack
viewtopic.php?f=108&t=14190As for getting a new steering rack to the US you may have an issue.
Lotus contact information for the affore mentioned parts:-
Aidan Coughlan is Dealer Liaison UK & Europe
acoughlan@lotuscars.co.uk (If you have any issues with this email addy let me know)
Lotus Cars Limited
Potash Lane,
Hethel,
Norwich,
Norfolk,
NR14 8EZ
T +44 01953 608279
F +44 01953 608253
Aidan will let you know if the part is still available, but I would ring them because he will be able to answer more questions about shipping. (Lotus don't normlly ship to private addresses in the US, but he may ship to Dave Bean???
Let us know how you get on and I'll try and give some guidance.
TTFN
If you have a problem, if no one else can help, and if you can find them, maybe you can hire... The N/A-Team.