940 Non-turbo

I forgot to mention in my earlier post when I posted my problem about my water pump. Incidentally my steering rack has been R & R for 4 times in this year. First they did a rebuilt but leaked again a couple weeks later. Took back to the mechanic and he did another round of rebuilding with a new kit. No luck, leaked again in another couple of weeks. Third time round he put in a used rack that lasted longer but still leaked.

Changed mechanic and the new mechanic brought in another used rack. Guess what? Leaked profusely, like having to top up daily. So the mech ordered another used rack. This time it lasted two months. Warranty expired. Now mech wants to rebuild because it is cheaper to do so.

Should I go on with rebuilding and replacing with used rack or should I just go get a new rack (expensive option)?

I am considering doing the job myself to save some money. I do not have the tools to carry out the rebuilding so my only option is to get a used rack and fit it in myself. I've read here that this is a feasible option for DIYer. If I buy from the yard what should I be looking for, like how to spot a leak and what obvious sign to take note? What to look for to ensure that the used unit is in good working condition? What simple tests should I do to pick a reasonably good unit? Used item here carries a warranty period of one week only.

Please help. I've spend quite a bit on this steering rack problem to date.
BTW the work is done by Volvo mechanics not volvo dealers so most of the returning R & R are not FOC.

Thanks again.

Laozong