Senior needs help with my work outs.

I joined a gym this summer. I'm 63 male, 5 ft 11 & over weight. I was 260 lbs, but it's down to 246 lbs now.
I have been focusing on cardio work outs, for past two months. I've had a total knee replacement so no running or squats!
I use an elliptical or arc trainer for my cardio sessions.
Mon-Wed -Friday are my cardio-days. Fridays I change up the cardio with a HIIT session on elliptical.
I'm doing 40 minutes, & about 700 calories burn per session.
For past month Tues & Thurs are strength training days.
I'm doing 3 sets of 8 reps.
Lat Bar Pull Down 150 lbs
Bench press : 150 lbs
Seated Row : 150 lbs
Over head Press: 150 lbs
Seated Leg Press: 200 lbs
Back Flexing machine: 125 lbs 25 reps
Upper ab crunch machine: 3x 10 & 125 lbs.

I have had some history of lower back strain so I'm staying away from Dead lifts for the time being.
My goal is to improve my overall health, trim the fat primarily, preserve & improve my strength & muscle mass.
I am not sure at my age what gains in strength or muscle mass are reasonable.
I do not seem to be making any gains with my strength, ie cannot get more reps or higher weight.
I could use some help? Should I try higher weight, less reps?
I forgot to add, my target weight is 230 lbs. The reps above are not to failure, but are close, have maybe 1-2 more reps left.
Well whatever I'm doing, it's working. Last November (black Friday my wife & I finally upgrade our cell phones to smart phones) we added the MyFitnessPal app to our iphones. Tracking our calorie intake is easy with it & I track my workouts with a Fitbit.
I have decided to ignore any strength gains until I reach, my new target weight of 225 lbs.
This week I weighed in at 234 lbs. So I'm just 9 lbs from my new target.
firstly, well done on your loss so far :) the strength training you have been doing will have minimised muscle loss and maximised fat loss while in a calorie deficit which is great !

reps and sets will depend a lot on your goals, strength gains require low reps higher weight and is ideal for maintaining muscle while dieting to drop fat. To build muscle mass you need higher reps with slightly lower weight.
I'm trying to keep things from getting too boring.
As I stated in my OP I've had a TKR (total knee replacement) which eliminates running, due to the impact.
However, I can walk freely up to about 3 mph pace.
So I have added Incline walking to my cardio repertoire.
I have found I can get my HR up to 140 bpm, by inclining the treadmill up to 13-14° and maintaining a pace of 2.7 mph.
My current routine is as follows:
Monday: 45 minutes: Incline walking
Tuesdays : chest press, lat bar, seated row, o'head press, 20 min cardio on elliptical.
Wednesday: 45 minutes on arc trainer.
Thursday: Seated Leg Press, Back Flexing machine, Upper ab crunch machine, 20 min cardio on elliptical.
Friday: 20 min straight cardio, followed by 20 min HIIT cardio on elliptical.
weekends: rest.
I log my work outs & calorie intake using my Fitbit Charge HR & MyFitnessPal app on my iPhone.
I maintain a 600 to 1000 calorie deficit each day, weekdays. Pretty much zero on weekends.
Checked my weight yesterday & again this morning, to make sure I wasn't dreaming. 227 lbs!!!!,
Just 2 lbs to go.
I have noticed the calculated calorie burn is down from 600-700 calories/session to 500-600 calories for same time period.
I attribute this to the weight loss.
2 more weeks to go & then a week of Rec, Fun & Sun in Cancun. Mx
I will be snorkeling, scuba diving, & right arm curls (raising glass from bar to my mouth) "cervesa por favor": LOL
I will ignore diet/alcohol restrictions for this week for the most part. When I get home I will weigh-in again & get back to work.
New target is 210 LBS.
When I get back from Cancun, I'll (no doubt in my mind) be back at the gym & tracking my calorie intake once again.
Pinching my middle I think the target of 210 lbs is a must.
That said, I know the 30+ lbs I've lost has also been some muscle mass.
Currently I'm running 500-600 calorie deficit/day.

Thinking ahead, to build some muscle mass, I' need some advise on calorie intake & my workouts.
I'm assuming more resistance/weight training & less cardio (currently 5 days/week) & a calorie surplus.
Based what I've been doing , more weights & less cardio will reduce the deficit somewhat.
What to change & how much is what I need to know?
No I don't. Sorry. It's been some years, but as I recall I need to have various measurements, checked with a fat caliper.
Just an update on my weight training: my chest/bench press is down , but others are up.
I'm doing 3 sets of 8-10 reps.
Lat Bar Pull Down 160 lbs up 10)
Bench press : 120 lbs (down )
Seated Row : 160 lbs
Over head Press: 120 lbs
Seated Leg Press: 220 lbs (up 20)
Back Flexing machine: 125 lbs 25 reps
ab crunch machine: 3 x 20 @ 145 lbs. (20 center & 20 each oblique)
Bench press involves a lot of technique, and uses more muscle than most people think. grip width, elbow position, bar path, arch, core strength, back strength, foot placement and leg drive all have an effect on how much you can bench.