Remember having read, that early in Barbarossa the Germans sent broken tanks all the way to Germany for repairs. Later on they had repair crews to get the tanks working as fast as possible. I think this was in Kiev 1941 by Stahel Any knowledge by others how the repair work went, was there a difference early and later in war?
I have heard that rebuilds of heavily damaged AFV's squewer the overall production numbers as they went back to factory.
There was significant difference. See CMH Pub 104-7 German Tank Maintenance in World War 2. Part of the US Army German Papers written for them by 'tame' German generals at the end of the war. I don't have the link any more having down loaded a copy but a search should take you to it - its about 60 pages and worth a read.
The books you need, Kai, are Friedli's 'Repairing the Panzers' V1 & 2. Sadly, they've only very recently become stupidly expensive, so hopefully Panzerwrecks will reprint some time soon. really sort of brilliant nerdish focus on something that ought to have more coverage, for Allied & Axis. He outlines in some detail the different levels of maintenance orgs, but a quick paraphrase of the 'Heimat' repair section here: Heavily damaged - beyond the abilities of Werkstatt. Sent to closest Heereszeugamt, which then forwarded to the manufacturers. 1941 these depot were in Breslau, Konigsberg, Magdeburg, Mainz & Wein. 1942 onwards, new level of maintenance established between more local repair & Homeland. 'K-Werk' (Panzer-Instandsetzungs-Kraftfahr-Werk) which Werlin told Keitel was essential, given 300,000 (?!) vehicles needing regular repair. Basically moving some Manufacturer level facilities closer to the front. First MAN, DB & Krupp - Civvy workers. Equipped for long-term maintenance & complete rebuilds. He covers a specific report from MAN about K-Werke in Riga, Smolensk & Dnjepropetrowski. Feb-March '42, details plan to repair total 1050 AFVs at these depots with c.70/month coming out of Riga with a need for c.310 employees & associated machine tools there. Serious issues found at those three Werke by the end of '42. Many sent on to Breslau as repair impossible. Evacuated several times as the front retreated, Notes in V1 that there's more detail in V2, but can't find my copy, which is... concerning.)