I did a quick search, and am awaiting to here back from Tektronix regarding this part number in particular, as I assume you have though will log the info I found for future reference since I am still early on in the learning curve:
Here is a lead that may have and is new to me (note there is contact info under the May 2017 entry):
http://wonghoi.humgar.com/blog/category/measurement-equipment/Info from same person on pots:
https://forum.tek.com/viewtopic.php?t=137709Two other potential sources I've read before though never contacted:
http://www.fetaudio.com/archives/1135https://www.qrz.com/db/VK2BLCHere is a compilation of links of images I found with different revision potential info:
https://www.eevblog.com/forum/repair/tds744a-('a'-is-for-adventure)/https://www.eevblog.com/forum/repair/need-help-repair-tektronix-tds520b/?allhttps://www.ebay.com/itm/Tektronix-Power-supplier-unit-for-TEKTRONIX-TDS-784D-TDS-784C-Working-/251222585433?_trksid=p2349526.m4383.l4275.c4https://www.ebay.ca/itm/Tektronix-CRT-driver-board-678-1402-12-for-TDS-524A/260838720110?hash=item3cbb33026e:g:IvEAAOxyxpxQ7nZRhttps://www.ebay.com/itm/High-voltage-CRT-power-supply-678-1402-10-for-Tektronix-TDS724/142504440525?epid=1675346159&hash=item212ded32cd:g:EwsAAOSwNSxVT1vnhttps://www.ebay.ca/itm/High-voltage-CRT-power-supply-678-1402-10-for-Tektronix-TDS724/142504440525?hash=item212ded32cd:g:EwsAAOSwNSxVT1vnhttps://www.ebay.ca/itm/Tektronix-CRT-driver-board-678-1402-09-for-TDS-744A-Working/251407195447?hash=item3a89095d37:g:aosAAMXQRDxREjpUhttps://www.ebay.ca/itm/Tektronix-TDS-700-7xx-Series-Oscilloscope-Color-CRT-and-Display-Driver/152485736085?hash=item2380dbae95:g:GsgAAOSwCU1Y1vEb (678-1402-09)
https://www.ebay.ca/itm/Tektronix-CRT-driver-board-678-1402-08-for-TDS-744A-Working/251206237099?hash=item3a7d0efbab:g:ExgAAOxyEdlQ3xaUhttps://www.ebay.ca/itm/Tektronix-CRT-driver-board-678-1402-07-for-TDS-684A/260810076922?hash=item3cb97df2fa:g:fagAAMXQUY1Q9vrShttps://www.ebay.ca/itm/High-voltage-CRT-Power-Supply-678-1402-06-for-Tektronix-TDS784A-671-2374-01/282696880877?hash=item41d20c12ed:g:Zu4AAOSwlmtZ5Ph4https://www.ebay.ca/itm/Tektronix-CRT-driver-board-672-1402-06-for-TDS-544A/261100646275?hash=item3ccacfaf83:m:mCXcmiNttjUfo2OjfVt6rkgThe link most everyone knows and a great source of information and inspiration (you to Jay et.al):
http://www.hakanh.com/dl/kits.htmCould use feedback:
https://forum.tek.com/viewtopic.php?f=568&t=137958Reply I received hunting down schematics from Tektronix before noting a previous reference to Artek Manuals:
Some customers have had success using one or more of these contacts:
--The Boat Anchor Manual Archive
http://bama.sbc.edu/ or The Boat Anchor Manual Archive Mirror:
http://bama.edebris.com/manuals/--Bitsavers.org
http://bitsavers.org/pdf/tektronix/--Manoman.sqhill.com
http://manoman.sqhill.com/tek.php--Classic Tek
http://classictek.org/--Instrumentation and Metrology Labs
Phone: 877-357-5900 or 603-929-9990, Fax: 603-929-1329
Email: sales@imltest.com Web:
www.imltest.com-- Manual Merchant: Linda Kaplan, P.O. Box 927792, San Diego, CA 92192-7792
Phone: 858 642-0785 Fax: 858 642-0885 Fax
Web:
www.manualmerchant.com Email: linda_p@ix.netcom.com
-- W7FG Vintage Manuals, 3300 Wayside Dr., Bartlesville, OK 74006
Phone: 800-807-6146,
Web:
www.w7fg.com-- Manuals Plus, P.O. Box 549, TAD #601, Tooele, Utah 84074, Fax,
Phone: 1-800-345-4019 or 801-936-7000 Fax: 801-936-7004
Web
www.manualsplus.com-- A G Tannenbaum, A. G. Tannenbaum P.O. Box 386 Ambler, PA 19002
Phone: (215) 657-0106 Fax: (215) 657-0520
Web
www.agtannenbaum.com-- J Dosher Manuals (in UK):
Web:
http://www.jdosher.pwp.blueyonder.co.uk/ email: jdosher@blueyonder.co.uk;
-- Tom Gootee: email tomg@fullnet.com
Web:
http://www.fullnet.com/u/tomg/manuals.htm--Bill & Stan's Tektronix Resource Site
Email: w7ni@easystreet.com
Web:
www.reprise.com/host/tektronix/home--Analog Services Inc
Phone: 270-276-5671 Fax: 270-276-5588
Web
http://www.logwell.com/index.html--Big-List.com
http://www.big-list.com/usedmanu.html--Techrecovery used instruments
Phone: 877-837-8872
Web:
http://www.techrecovery.com/-- Sphere Research Canadian Test Equipment
Web:
http://www.sphere.bc.ca/test/ecg.html-- Consolidated Surplus
Web:
www.consolidatedsurplus.com