Efficient Reconstruction of Cost Basis for Securities

QuickUser364623

I have a 401(k) account which needs to have the cost basis fixed. I had some placeholder entries and, like a dumb@ss, deleted them to see what would happen. The account was opened about seven or eight years before I started tracking it with my current Quicken file, so there is a fair number of transactions underlying the cost basis. However, I have the lion's share of those transactions in a separate (no longer used due to corruption) Quicken file.
Searching here, most of the stuff I find in re: handling placeholder entries and fixing cost basis does not seem to be super-helpful, at least given my limited Quicken skilz. In particular, I am not experienced with Quicken file import/export. Based on this:
https://www.quicken.com/support/how-do-i-importexport-quicken-transfer-format-qxf-file
it looks like this might be a way to quickly and efficiently capture most of what I would want to capture, but I'm wondering if any of the very savvy users here might be able to clue me in one way or another. Basically I have about seven years worth of transactions I would like to quickly and efficiently import, is this the best way?

Sherlock

If you care about tracking the investment performance for the past seven or eight years, importing an accurate history is the way to go.  If you haven’t already, you may want to review: http://www.quicknperlwiz.com  

If you’re simply interested in tracking the performance moving forward as this is a 401(k), you could use a Removed and Added transaction for each security currently held to establish the correct average cost basis.