With the help of this web site and your valuable suggestions,I have already completed my 45k25 table and knee lift projects.
I would like to thank member nickname “jimi” for sharing machine table size post at
https://leatherworker.net/forum/topic/74406-singer-45k-treadle-base-parts-information-or-parts-list/
by means of this subject I could reshape my old fur sewing table with jigsaw.
and also member nickname “friquant” for valuable video sharing . Even though I know knee lifter mechanism ,I could not imagine application with chain, and watching this video made my work.
I bought an original Singer knee mechanism from one of dealers in my city,but I couldn’t find the hook like part,instead of this I used allen no 7 and 1.5 . I drilled a hole on 7 and inserted into allen 1.5 as “hook” for pulling chain mechanism.
I tried and it seems working. Thank you 👍