PARTS Help Please

[dpdiver]

Good evening, glad to be back! Hope everyone doing well. I just found a 1997 Nissan Hard Body 2.4 2wd KA24E in great condition!
Only thing is a horrible lifter noise from the top of the engine. We took the valve cover off to find the rear most left intake rocker
arm was floating freely around the valve stem/cam because the "retainer clip" is broken off (found it 3 pieces)). The top of the valve stem
has been flattened badly. I have not been able to find the part name or numbers for the rocker arm retainers?? Also I would need to
order a rear? intake rocker arm? Is their anyway to repair a little bit of the top of the valve stem to make it a bit longer again....temporally?
Like a spot of weld/tap? Thank you forum, any advice would be greatly appreciated! Thank You