I had the same problem with scrambled screen when converting HDMI to Component. Described here in couple of occasions. The HDFury2 device solved the problem and I enjoy streaming my cable using M1 in HD through Component input (YPbPr).
From your message it seems you are attempting to convert from SCART to Component using HDMI, That is silly because it make no sense as SCART carry only SD (Standard definition) picture quality. For High Definition (HD) you need to convert from HDMI of your source to Component for M1/M2. For this you have to use device I mentioned at the beginning of my post, unless your source already have component (YPbPr) output. Then just connect directly to Slingbox. Hope it helps.
Slingbox has no RGB input, it has Component input YPbPr. Although the RCA inputs are color marked as Red-Green-Blue, this is not RGB, so using RGB (SCART-RGB) source wont work. In general sources equipped with SCART do not provide component signal (YPbPr) , only Composite, S-Video or RGB. All three are NOT high definition. So only high definition source quipped with HDMI or Component output provide high definition signal for your M1/M2. Again, for HDMI you must use HDFury2 to convert from HDMI to component as other converters including one advertised by Slingmedia does not work in 99% cases. Good luck.