The Dish Network User's Resource
I was told by a Dish engineer that the change was made in the manufacturing line at some time in early November.
If that's true, then it's a simple matter to avoid the jaggies. A DISH unit's date of manufacture is hidden in the receiver's serial number. (Not the “R00...” number- DISH calls that the “CAID”, or Conditional Access ID.) The number that DOESN'T appear on the info screen- the combination of letters and numbers which appear on the receiver's boilerplate (the sticker near the power cord)- is the “serial number”. A 4700 is numbered R(p)(b)CU(y)(nnnnn)(m), where...
p=manufacturing plant- probably unimportant here
b=“brand”- probably also unimportant here, but AFAICT, E=“Echostar”, T=“HTS” (Houston Tracker), P=“Philips”, etc.
y=year code. G=97, H=98, J=99, K=00. (Note they skipped “I”.)
nnnnn=serial number, sequential starting from 00001 each month.
m=month. A=Jan, B=Feb, etc. etc. etc. (They skip “I” here as well. I suppose it would look like a “1”, so Sep=J, through Dec=M.)
So ANY CUKnnnnnm should be fine, (built in 2000) as well as CUJnnnnnM (Dec. 99). If the change was early in November, then MOST CUJnnnnnL should be jaggy free, but avoiding those might be prudent.
For those who care, the “CU” also indicates information. “C” indicates generation: in this case, 3rd generation, as opposed to “A” (2000s) or “B” (3000, 4000, 5000, etc. Interesting to note here that DISHPlayers are B's!)
The “U” indicates model. “U” is probably for UHF, since the 3000 was a “BI”
(IR only) and 4000 (like the 4700, also UHF) was a “BU”. (In the interest of semi-completeness, BN is a 1000, AB is a 2000, BT is a 5K, CL is a 2700, CM is a 3700, CN is a 3800, BW is a 7100 and BP is a 7200. (It will be interesting to see if 3900s and 4900s get new letters, or if they keep 3800 and 4700 serial numbers.)
While you are still bored, the “R” the serial # starts with seems to be for a “new” receiver- “W” and “S” have shown up on refurbs, but I don't know what differentiates a W from an S.