This project was completed a few years ago, just posting a few photos of the re-cap and general cleanup/alignment.
Below is Crown promotional material from April 1975 (the approximate age of this unit) describing the CX and SX electronics as well as the 800 series transport. The unit I worked on is the simpler SX electronics and more sophisticated Pro 800 series transport, 2 channel, 4 track (hence the 824 model).
This shows the main audio board before any work. Note there are a number of tantalum caps (green and orange) on this PCB, mostly for audio coupling. These caps fail by shorting, potentially causing fire and other catastrophic problems. They also have poor audio characteristics. Along with all electrolytics (which are now beyond their life expectancy), the tantalums are all being replaced.
The same PCB after re-cap. I used Nichicon Muse bi-polar electrolytics (the green caps) for all coupling locations. On the far left the horizontal white caps are new 1% polystyrene film caps for equalization.
On the lower left, you can barely see that the original phone jacks for line input and output have been replaced with gold/teflon RCA jacks for easier compatibility with modern consumer electronics.
The underside of the audio PCB, showing the new 0.1uf polypropylene bypass caps on all the electrolytics.
Sorry, no photos of the transport section before the re-cap. This shows that section after the re-cap. New electrolytics on the motion sensor PCB at the top, as well as new motor run caps under the take-up and supply motors.
Transport control PCBs after the re-cap, mostly Panasonic and Nichicon electrolytics.
A closeup of one of the new motor run caps.
The head assembly, before replacing the pinch roller on the right.
View of the rear of the unit showing the new line input and output RCAs.
Rear view of the unit after all work. You can see the belt from the capstan motor (smaller pulley) to the capstan on the left, and the belt that drives the mechanical tape counter at the top center and left.
Here's what the road case looks like all buttoned up for transport. The front and rear doors come off for use.
Finished unit, in its transport case, powered up, tape counter at the top. Since the Crown decks don't have locking tape spindles, I used a pair of Otari locking NAB hubs on this unit.