Here are some photos of the bolt. The extractor seems to be serialized, and might be the single non-matching part of the gun.
For the sake of research, I decided to open up Anthony Chan's
Arming the Chinese: The Western Armaments Trade in Warlord China, 1920 - 1928 to the section on Czechoslovakian trading. Multiple shipments are mentioned, but one stuck out to me.
On 14 October 1925 a consignment of 81,000 rifles and 40 million rounds of ammunition arrived in Yingkou from the State Brno Arms Factory with the Czech Ministry of National Defense conducting the negotiations. The National Defense Minister and Dr. Beneš publicly sanctioned this consignment. - Chan, Pg. 85
The recipient of this order was Zhang Zuolin, leader of the Fengtian Clique. The official nature of this transaction, along with the explicit mention of Brno gives me the impression that this shipment included brand new rifles. The serialized trigger guard being a feature circa 1925 could place this specific Vz. 24 in that shipment.
The other Czechoslovak shipments mentioned include 40,000 rifles sent in early 1928, and 15,000 sent "later" to Zhang Zhongchang and Sun Chuanfang, the warlords who succeeded Zhang Zuolin after his assassination. Though the book makes no explicit mention of Brno's involvement in these orders.