wastegate? turbo problem? anyone?

[glider]

I am newish to a 83'300sd and have read many posts on wastegate adjustment etc. I took the whole turbo/exhaust manifold off because I could not find the spring/slinky on the wastegate cover (oh well...) made a thin wrench (by way of bench grinder) found that I could turn the threads all the way in until the adj.nut bottomed out...(4 threads) put it all back on and it worked! increased the boost! but, I was hoping for more...(being human) added a boost guage and went from around 8psi-10psi...I did notice an increase in power but I have read that it should go higher if you adjust the wastegate ? so my question is ; is my wastegate leaking? or is the turbo getting tired? (I guess that's two ?s) I haven't seen much to believe the turbo is to blame as they seem to rarely fail...can someone give me a tip? I would like to do whatever I can (like valve adj.,filters,timing etc.) to get the most out of this rig but lack much experience with diesels...Thanks for any info! Mike