Tabby to answer your question, is not really easy. There is nothing really big wrong with the Norincos (same thing as a Polytech). There are some small issues, the biggest being the bolt. Which is actually blown out of proportion.
So having done a bit of Polytech research prior to getting my 3 Polys, here is what I can give you as far as information.
The Good:
Polys/Norincos have good, dimensionally correct receivers. Contrary to many reports, their receivers are made with the proper steel, and while not hardened quite as much as as USGI receivers, they are adequate. If you plan on scoping one, you will have a much easier time than doing the same to a Springfield M1A.
They have forged one piece op rods, and trigger housings. Chrome lined barrels and their barrels are considered to be good .
The Not So Good:
Some Polys have issues with these items. Not all, but some. Your rifle may have none of these issues, or all of them.
#1. Rear sight knobs can be soft. Easy fix. Replace with USGI knobs. Either M14 knobs (marked up to 10 and with an M) or Garand knobs (marked up to 12). My recommendation is to not use knobs marked WCE(except Garand knobs). All Chinese made knobs are marked WCE. You don't want to replace bad/soft Chinese made knobs with more Chinese made knobs.
#2. Hammer and trigger may be soft. Again, easy fix. Replace with USGI parts, either M14/M1A or Garand. Chinese triggers and hammer are unmarked. USGI parts are marked with part/drawing numbers.
#3. Op Rod spring may be a bit undersized. Easy fix. Replace with GI spec spring.
#4. Early stocks were made of Chinese Chu wood. Ugly, and soft. Easy fix. Replace with USGI. Some of the later stocks were walnut.
#5. The biggie. The bolt. Chinese bolts were made from the wrong alloy(primary problem), lugs were cut to the wrong profile(secondary problem), improperly heated treated, and the headspace was cut a bit long(similar to the US Navy 308 Garands the CMP is releasing). Nothing that will gaurantee longevity. Having said that, I don't believe that there has ever been a documented case of any kind of a bolt failure on a Polytech. Many, many owners shoot their Polys without one bit of headspace problems. My suggestion is to get a set of 7.62NATO headspace gauges and periodically check the headspace. Note also, Chinese bolts are unmarked on the top, while USGI bolts have a series of letters and numbers stamped into them. Who knows, you might actually get a Poly that has already had the bolt conversion done.
While the above list sounds expensive, it is not. With careful shopping, all the parts (save the bolt) can probably be had for less than $150. Since Springfields often cost upwards of $500+ more than a Polytech/Norinco you are often money ahead getting one of the Chinese rifles.
I have 3 Polys and have done all the above work to each one, whether they needed it or not. Though only one was having sight and trigger issues. I have had mine for better than 5 years. I actually had a Springfield M1A, and ended up selling it and going with the Polys.
As for the Springfields, they have their own issues, which often occur sporadically. They use a cast extractor which often breaks or disappears into orbit with in the first few hundred rounds. Often they come with a sticky chamber. Mine would not finish a 20 rd magazine with out one Failure To Extract. When I rebarreled my son's Polytech with a 18.5" Springfield Bush barrel and Springfield bolt, it was litterally every single round was stuck in the chamber. When we went back to the Chinese barrel and USGI bolt, all problems stopped. There have also been issues with the safety bridge. That is the part that cams the firing pin back just befoe the bolt rotates into position. This prevents slam fires.
additionally, SAI M1A receives are often out of spec on the exterior. Meaning, if you plan on scoping it, you may have a difficult, or impossible, scoping it or getting the scope to zero. The Chinese made rifles do not have this problem.
Now, SAI does have a lifetime warrenty on their guns, but there are people who have reported having to send their rifles back two and three times to get issues fixed. SAI has spotty Quality Control. I am quite happy with my 3 Polytechs, and while I haven't done any real accuracy testing, I do know they will work when I pull the trigger.
Here is my Polytech in its ProMag Archangel stock.